This tutorial will help you draw shapes using the pen using Custom Blocks.

Square

A square is very easy to draw. Use this custom block if you want it in the sprite's direction:\:

define square (size)
pen down
repeat (4)
move (size) steps
turn cw (90) degrees
end

If you always want it at 90°, then use this:

define square (size)
pen down
change x by (size)
change y by (join [-] (size))
change x by (join [-] (size))
change y by (size)

Your sprite will now draw a square when you run the block.

Rectangle

A rectangle is only slightly harder to draw. Use this block:

define rectangle height (height) width (width)
repeat (2)
move (width) steps
turn cw (90) degrees
move (height) steps
turn cw (90) degrees
end

Your sprite will now draw a rectangle when you run the block.

Circle

A circle is is slightly harder to draw than a rectangle. Use this block:

define circle (size)
repeat (round ((360)/(size)))
move (size) steps
turn cw (size) degrees
end

Your sprite will now draw a circle when you run the block.