There's the link to it.
Good luck with building it! what is a dd???
my dad made two learning towers (one for our house and one for theirs) with a total investment of about $75 (a sheet of birch, and green (not color, but safe) paint.
he has thousands of tools, though, including a skill saw, which he used. he made it pretty close to exactly like the real learning towers, and we're very happy with them!
if you want a picture you can PM me