diff --git a/HISTORY.md b/HISTORY.md
index 8ff29cd4..908ce65f 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -68,6 +68,9 @@
     * Chinese, thanks, Simon!
     * Brazilian Portuguese, thank you, Cassiano D'Andrea!
 
+### 2021-11-30
+* blocks, threads: block-assembly support, experimental
+
 ### 2021-11-29
 * renamed "r-g-b-a" option to "RGBA" and "r-g-b(-a)" to "RGB(A)"
 
diff --git a/snap.html b/snap.html
index 4f633cae..c92e171a 100755
--- a/snap.html
+++ b/snap.html
@@ -16,8 +16,8 @@
         <script src="src/morphic.js?version=2021-07-09"></script>
         <script src="src/symbols.js?version=2021-03-03"></script>
         <script src="src/widgets.js?version=2021-17-09"></script>
-        <script src="src/blocks.js?version=2021-11-27"></script>
-        <script src="src/threads.js?version=2021-11-27"></script>
+        <script src="src/blocks.js?version=2021-11-29"></script>
+        <script src="src/threads.js?version=2021-11-29"></script>
         <script src="src/objects.js?version=2021-11-26"></script>
         <script src="src/scenes.js?version=2021-11-24"></script>
         <script src="src/gui.js?version=2021-11-27"></script>
diff --git a/src/blocks.js b/src/blocks.js
index 10ef8c75..f0ca75fe 100644
--- a/src/blocks.js
+++ b/src/blocks.js
@@ -153,14 +153,14 @@ radians, useBlurredShadows, SpeechBubbleMorph, modules, StageMorph, SymbolMorph,
 fontHeight, TableFrameMorph, SpriteMorph, Context, ListWatcherMorph, Rectangle,
 DialogBoxMorph, BlockInputFragmentMorph, PrototypeHatBlockMorph, WHITE, BLACK,
 Costume, IDE_Morph, BlockDialogMorph, BlockEditorMorph, localize, CLEAR, Point,
-isSnapObject, PushButtonMorph, SpriteIconMorph, Process, AlignmentMorph,
+isSnapObject, PushButtonMorph, SpriteIconMorph, Process, AlignmentMorph, List,
 CustomCommandBlockMorph, ToggleButtonMorph, DialMorph, SnapExtensions*/
 
 /*jshint esversion: 6*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.blocks = '2021-November-27';
+modules.blocks = '2021-November-30';
 
 var SyntaxElementMorph;
 var BlockMorph;
@@ -3614,6 +3614,8 @@ BlockMorph.prototype.restoreInputs = function (oldInputs, offset = 0) {
     return leftOver;
 };
 
+// BlockMorph helpscreens
+
 BlockMorph.prototype.showHelp = function () {
     var myself = this,
         ide = this.parentThatIsA(IDE_Morph),
@@ -3702,6 +3704,41 @@ BlockMorph.prototype.exportResultPic = function () {
     }
 };
 
+// BlockMorph components - EXPERIMENTAL
+
+BlockMorph.prototype.components = function () { // +++
+    throw new Error('subclass responsility');
+};
+
+BlockMorph.prototype.copyWithInputs = function (inputs) {
+    var cpy = this.fullCopy(),
+        slots = cpy.inputs(),
+        dta = inputs.itemsArray().map(inp =>
+            inp instanceof Context ? inp.expression : inp
+        );
+    slots.forEach(slt => {
+        if (slt instanceof BlockMorph) {
+            cpy.revertToDefaultInput(slt);
+        }
+    });
+    dta.forEach((inp, i) => {
+        if (inp instanceof BlockMorph) {
+            if (inp instanceof CommandBlockMorph && slots[i].nestedBlock) {
+                slots[i].nestedBlock(inp);
+            } else {
+                cpy.replaceInput(slots[i], inp);
+            }
+        } else {
+            if (inp instanceof List && inp.length() === 0) {
+                nop(); // ignore, i.e. leave slot as is
+            } else {
+                slots[i].setContents(inp);
+            }
+        }
+    });
+    return cpy;
+};
+
 // BlockMorph code mapping
 
 /*
@@ -5417,6 +5454,46 @@ CommandBlockMorph.prototype.extract = function () {
     }
 };
 
+// CommandBlockMorph components - EXPERIMENTAL
+
+CommandBlockMorph.prototype.components = function () { // +++
+    var seq = new List(this.blockSequence()).map(block => {
+        var expr = block.fullCopy(),
+            nb = expr.nextBlock(),
+            inputs, parts;
+        if (nb) {
+            nb.destroy();
+        }
+        expr.fixBlockColor(null, true);
+        inputs = expr.inputs();
+        if (!inputs.length) {
+            return expr;
+        }
+        parts = new List([expr]);
+        inputs.forEach(inp => {
+            var val;
+            if (inp instanceof BlockMorph) {
+                parts.add(inp.components());
+            } else {
+                val = inp.evaluate();
+                parts.add(val instanceof BlockMorph ? val.components() : val);
+            
+            }
+            expr.revertToDefaultInput(inp, true); // empty
+        });
+        return parts;
+    });
+    return seq.length() === 1 ? seq.at(1) : seq;
+};
+
+CommandBlockMorph.prototype.copyWithNext = function (next) {
+    var exp = this.fullCopy(),
+        bottom = exp.bottomBlock(),
+        top = next.fullCopy().topBlock();
+        bottom.nextBlock(top);
+        return exp;
+};
+
 // CommandBlockMorph drawing:
 
 CommandBlockMorph.prototype.outlinePath = function(ctx, inset) {
@@ -6180,6 +6257,32 @@ ReporterBlockMorph.prototype.userDestroy = function () {
     this.destroy();
 };
 
+// ReporterBlockMorph components - EXPERIMENTAL
+
+ReporterBlockMorph.prototype.components = function () { // +++
+    var expr = this.fullCopy(),
+        inputs = expr.inputs(),
+        parts;
+    expr.fixBlockColor(null, true);
+    if (!inputs.length ||
+            inputs.every(slot => slot.isEmptySlot && slot.isEmptySlot())) {
+        return expr;
+    }
+    parts = new List([expr]);
+    inputs.forEach(inp => {
+        var val;
+        if (inp instanceof BlockMorph) {
+            parts.add(inp.components());
+        } else {
+            val = inp.evaluate();
+            parts.add(val instanceof BlockMorph ? val.components() : val);
+        
+        }
+        expr.revertToDefaultInput(inp, true); // empty
+    });
+    return parts;
+};
+
 // ReporterBlockMorph drawing:
 
 ReporterBlockMorph.prototype.outlinePath = function (ctx, inset) {
diff --git a/src/threads.js b/src/threads.js
index 3be3dbdb..b0d9c8db 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -64,7 +64,7 @@ SnapExtensions, AlignmentMorph, TextMorph, Cloud, HatBlockMorph*/
 
 /*jshint esversion: 6*/
 
-modules.threads = '2021-November-27';
+modules.threads = '2021-November-30';
 
 var ThreadManager;
 var Process;
@@ -7009,6 +7009,20 @@ Context.prototype.isInCustomBlock = function () {
     return false;
 };
 
+// Context components - EXPERIMENTAL
+
+Context.prototype.components = function () {
+    var expr = this.expression.components(),
+        parts;
+    if (!this.inputs.length) {
+        return expr;
+    }
+    parts = new List();
+    parts.add(expr); // blocks / other
+    this.inputs.forEach(name => parts.add(name));
+    return parts;
+};
+
 // Variable /////////////////////////////////////////////////////////////////
 
 function Variable(value, isTransient, isHidden) {