Oh, I just thought of something!
Did you see my video from the Spezi show?
http://www.velovision.com/showStory.php?storynum=1175
At about 3m 12s, is the cutest homebuilt child's recumbent I've ever seen. It's a brilliantly simple adaptation of a small Puky bike, with a pair of adult bike forks forming the boom, the dropouts are around the original BB axle, the fork crown is bolted to the front of the Puky and a new BB welded on the top of the steerer tube of the forks. Add a plywood seat instead of the saddle, and a longer chain, and hey presto. Only one bit of welding in the whole thing.
Go on...
I may be able to dredge up photos sowing more detail if you want.