diff --git a/.gitignore b/.gitignore
index 2b15657..58fe583 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,4 @@ gh-pages/
 /dist
 /.clj-kondo/.cache
 /.clj-kondo/rewrite-clj
+/plugins/demo/resources/public/js/
diff --git a/bb.edn b/bb.edn
index 802138b..f355484 100644
--- a/bb.edn
+++ b/bb.edn
@@ -2,10 +2,14 @@
         #_{:local/root "../sci.nrepl"}
         {:git/sha "2f8a9ed2d39a1b09d2b4d34d95494b56468f4a23"}
         io.github.babashka/http-server
-        {:git/sha "b38c1f16ad2c618adae2c3b102a5520c261a7dd3"}}
+        {:git/sha "b38c1f16ad2c618adae2c3b102a5520c261a7dd3"}
+        io.github.scittle/build
+        {:local/root "build"}
+        io.github.babashka/scittle.datascript {:local/root "plugins/datascript"}}
 
  :tasks
- {:requires ([babashka.fs :as fs]
+ {:requires ([scittle.build :as build]
+             [babashka.fs :as fs]
              [cheshire.core :as json]
              [babashka.process :as p :refer [process]])
 
@@ -15,8 +19,7 @@
                    (fs/delete-tree ".shadow-cljs"))}
 
   shadow:watch {:doc "Development build. Starts webserver and watches for changes."
-                :task (clojure {:extra-env {"SCI_ELIDE_VARS" "true"}}
-                       "-M:dev -m shadow.cljs.devtools.cli watch main")}
+                :task (build/build *command-line-args* {:action "watch"})}
 
   http-server {:doc "Starts http server for serving static files"
                :requires ([babashka.http-server :as http])
@@ -34,8 +37,7 @@
                  (deref (promise)))}
 
   prod {:doc "Builds production artifacts."
-        :task (clojure {:extra-env {"SCI_ELIDE_VARS" "true"}}
-                       "-M:dev -m shadow.cljs.devtools.cli release main")}
+        :task (build/build *command-line-args*)}
 
   dist {:doc "Prepare dist folder for npm package"
         :depends [prod]
diff --git a/build/deps.edn b/build/deps.edn
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/build/deps.edn
@@ -0,0 +1 @@
+{}
diff --git a/build/src/scittle/build.clj b/build/src/scittle/build.clj
new file mode 100644
index 0000000..8586003
--- /dev/null
+++ b/build/src/scittle/build.clj
@@ -0,0 +1,71 @@
+(ns scittle.build
+  "Provides bb tasks for building and releasing scittle"
+  (:require
+   [babashka.classpath :as classpath]
+   [babashka.fs :as fs]
+   [babashka.tasks :refer [clojure]]
+   [clojure.edn :as edn]
+   [clojure.string :as str]))
+
+(defn- feature-files
+  []
+  (filter fs/exists?
+          (map (fn [d]
+                 (fs/file d "scittle_plugin.edn"))
+               (classpath/split-classpath (classpath/get-classpath)))))
+
+(defn- read-configs
+  [files]
+  (->> files
+       (mapcat (comp edn/read-string slurp str))))
+
+(defn- build-cmd [cmd scittle-dir]
+  (let [files (feature-files)
+        feature-configs (read-configs files)
+        ;; Each ./src/scittle_plugin.edn has a ./deps.edn
+        feature-dirs (map (comp fs/parent fs/parent) files)
+        cmd' (if (seq files)
+               (format "-Sdeps '%s' %s"
+                       {:deps
+                        (merge (into {}
+                                     (map (fn [dir]
+                                            [(symbol (str (fs/file-name dir) "/deps"))
+                                             {:local/root (str dir)}])
+                                          feature-dirs))
+                               {'scittle/deps {:local/root scittle-dir}})}
+                       cmd)
+               cmd)]
+    (when (seq feature-configs)
+      (println "Building features:" (str/join ", " (map :name feature-configs)) "..."))
+    (if (seq feature-configs)
+      (apply str cmd'
+        (map (fn [m] (format " --config-merge '%s'" (pr-str (:shadow-config m))))
+             feature-configs))
+      cmd')))
+
+(defn- build*
+  [cmd]
+  (let [building-outside-scittle? (not (fs/exists? "shadow-cljs.edn"))
+        scittle-dir (when building-outside-scittle?
+                  (->> (classpath/get-classpath)
+                       classpath/split-classpath
+                       ;; Pull out scittle from local/root or git/url
+                       (some #(when (re-find #"(scittle/[0-9a-f]+|scittle)/src" %) %))
+                       fs/parent))]
+    (when building-outside-scittle?
+      (fs/copy (fs/file scittle-dir "shadow-cljs.edn") "shadow-cljs.edn"))
+    (let [cmd (build-cmd cmd (str scittle-dir))]
+      (println "> clojure" cmd)
+      (clojure {:extra-env {"SCI_ELIDE_VARS" "true"}} cmd))
+    (when building-outside-scittle?
+      (fs/delete "shadow-cljs.edn"))))
+
+(defn build
+  "Build scittle shadow builds using clojure cmd and commandline args. Features on
+  classpath are automatically added.
+
+  Options:
+
+  * :action - compile action, defaults to release, but may also be compile or watch"
+  [{:keys [action] :or {action "release"}}]
+  (build* (format "-M -m shadow.cljs.devtools.cli --force-spawn %s main" action)))
diff --git a/deps.edn b/deps.edn
index 58efc55..ec562ba 100644
--- a/deps.edn
+++ b/deps.edn
@@ -1,7 +1,7 @@
 {:paths ["src" "resources"]
-
  :deps
  {org.clojure/clojure {:mvn/version "1.11.1"}
+  thheller/shadow-cljs {:mvn/version "2.20.15"}
   org.babashka/sci {:git/url "https://github.com/babashka/sci"
                     :git/sha "a85c488ee45700bcbe67bc01ab1c27407fff7887"}
   #_{:local/root "../babashka/sci"}
@@ -19,8 +19,8 @@
   io.github.babashka/sci.configs
   #_{:local/root "/Users/borkdude/dev/sci.configs"}
   {:git/url "https://github.com/babashka/sci.configs"
-   :git/sha "bf8d209e4aeabb92cb1be04e3d8f789583d5f449"}}
+   :git/sha "33bd51e53700b224b4cb5bda59eb21b62f962745"}}
  :aliases
  {:dev
   {:extra-paths ["dev"]
-   :extra-deps  {thheller/shadow-cljs {:mvn/version "2.20.15"}}}}}
+   :extra-deps  {}}}}
diff --git a/plugins/datascript/deps.edn b/plugins/datascript/deps.edn
new file mode 100644
index 0000000..1454ae1
--- /dev/null
+++ b/plugins/datascript/deps.edn
@@ -0,0 +1,3 @@
+{:deps
+ {datascript/datascript {:mvn/version "1.3.12"}
+  io.github.babashka/sci.configs {:git/sha "33bd51e53700b224b4cb5bda59eb21b62f962745"}}}
diff --git a/plugins/datascript/src/scittle/datascript.cljs b/plugins/datascript/src/scittle/datascript.cljs
new file mode 100644
index 0000000..f3dac97
--- /dev/null
+++ b/plugins/datascript/src/scittle/datascript.cljs
@@ -0,0 +1,9 @@
+(ns scittle.datascript
+  {:no-doc true}
+  (:require [sci.configs.tonsky.datascript :refer [config]]
+            [scittle.core :as scittle]))
+
+(defn init []
+  (scittle/register-plugin!
+   ::datascript
+   config))
diff --git a/plugins/datascript/src/scittle_plugin.edn b/plugins/datascript/src/scittle_plugin.edn
new file mode 100644
index 0000000..09eae58
--- /dev/null
+++ b/plugins/datascript/src/scittle_plugin.edn
@@ -0,0 +1,12 @@
+[{:name scittle/datascript
+  :namespaces [datascript.core datascript.db]
+  :js "./scittle.datascript.js"
+  :shadow-config
+  {:compiler-options {:externs ["datascript/externs.js"]}
+   :modules
+   {:scittle.datascript
+    {:init-fn scittle.datascript/init
+     ;; From https://github.com/tonsky/datascript/issues/298#issuecomment-813790783
+     :prepend "globalThis.datascript = {};"
+     :depends-on #{:scittle}
+     :entries [datascript.core]}}}}]
diff --git a/plugins/demo/README.md b/plugins/demo/README.md
new file mode 100644
index 0000000..e9f58eb
--- /dev/null
+++ b/plugins/demo/README.md
@@ -0,0 +1,25 @@
+# Demo
+
+A demo project of a custom scittle build.
+
+See:
+
+- `bb.edn` with
+  - `:deps` which includes:
+    - a dependency on the `scittle.build` project to build scittle + custom features
+    - zero or more plugin dependencies
+    - helpers like static file server
+  - development `:tasks`. Run `bb dev` for development and `bb release` to produce release artifacts.
+- `deps.edn`: this only contains a dependency on scittle itself
+
+Available plugins are in the `plugins` directory inside the top level directory of this repo.
+
+Writing a plugin involves writing
+
+- SCI configuration (this can be shared with users in the [sci.configs](https://github.com/babashka/sci.configs) project
+- Adding a `scittle_plugin.edn` file on the plugin's classpath (e.g. in the `src` directory). This EDN file contains:
+  - `:name`, name of the plugin
+  - `:namespaces`: the namespaces exposed to SCI
+  - `:js`: the name of the produced `.js` module file
+  - `:shadow-config`: the shadow-cljs configuration specific to this plugin
+- A `.cljs` file with an `init` function which calls `scittle/register-plugin!`.
diff --git a/plugins/demo/bb.edn b/plugins/demo/bb.edn
new file mode 100644
index 0000000..516f478
--- /dev/null
+++ b/plugins/demo/bb.edn
@@ -0,0 +1,20 @@
+{:deps {io.github.babashka/scittle.build {:local/root "../../build"}
+        ;; datascript plugin
+        io.github.babashka/scittle.datascript {:local/root "../../plugins/datascript"}
+        io.github.babashka/http-server
+        {:git/sha "b38c1f16ad2c618adae2c3b102a5520c261a7dd3"}}
+ :tasks
+ {:requires ([scittle.build :as build])
+  watch   {:doc "Watch build"
+           :task (build/build {:action "watch"})}
+  serve {:doc "Starts http server for serving static files"
+         :requires ([babashka.http-server :as http])
+         :task (do (http/serve {:port 1341 :dir "resources/public"})
+                   (println "Serving static assets at http://localhost:1341"))}
+  -dev {:depends [watch serve]
+        :parallel true}
+  dev {:doc "Run compilation in watch mode and start http server"
+       :task (do (run '-dev {:parallel true})
+                 (deref (promise)))}
+  release {:doc "Release build (advanced compiled JS)"
+           :task (build/build {})}}}
diff --git a/plugins/demo/deps.edn b/plugins/demo/deps.edn
new file mode 100644
index 0000000..62915a5
--- /dev/null
+++ b/plugins/demo/deps.edn
@@ -0,0 +1 @@
+{:deps {io.github.babashka/scittle {:local/root "../.."}}}
diff --git a/plugins/demo/resources/public/index.html b/plugins/demo/resources/public/index.html
new file mode 100644
index 0000000..a48dfc4
--- /dev/null
+++ b/plugins/demo/resources/public/index.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <link rel="stylesheet" href="/css/style.css">
+    <script src="/js/scittle.js" type="application/javascript"></script>
+    <script src="/js/scittle.datascript.js" type="application/javascript"></script>
+    <script type="application/x-scittle">
+      (require '[datascript.core :as d])
+      (prn (ns-publics 'datascript.core))
+    </script>
+  </head>
+  <body>
+  </body>
+</html>
diff --git a/plugins/demo/shadow-cljs.edn b/plugins/demo/shadow-cljs.edn
new file mode 100644
index 0000000..47e5deb
--- /dev/null
+++ b/plugins/demo/shadow-cljs.edn
@@ -0,0 +1,32 @@
+{:deps
+ {:aliases [:dev]}
+
+ :dev-http
+ {8000 "classpath:public"}
+
+ :builds
+ {:main
+  {:target     :browser
+   :js-options
+   {:resolve {"react" {:target :global
+                       :global "React"}
+              "react-dom" {:target :global
+                           :global "ReactDOM"}}}
+   :modules
+   {:scittle {:entries [scittle.core]}
+    :scittle.nrepl {:entries [scittle.nrepl]
+                    :depends-on #{:scittle}}
+    :scittle.promesa {:entries [scittle.promesa]
+                      :depends-on #{:scittle}}
+    :scittle.pprint {:entries [scittle.pprint]
+                     :depends-on #{:scittle}}
+    :scittle.reagent {:entries [scittle.reagent]
+                      :depends-on #{:scittle}}
+    :scittle.re-frame {:entries [scittle.re-frame]
+                       :depends-on #{:scittle.reagent
+                                     :scittle}}
+    :scittle.cljs-ajax {:entries [scittle.cljs-ajax]
+                        :depends-on #{:scittle}}}
+   :build-hooks [(shadow.cljs.build-report/hook)]
+   :output-dir "resources/public/js"
+   :devtools   {:repl-pprint true}}}}