Last year my children and I built a Sea Flea, for my daughter, and at that time cut out the required parts for a second Sea Flea for my son. We have finished putting together the second kayak, and launched it last weekend. So, I guess that makes this the start of a "Sea Fleat".....

Both kids had a blast zipping around and crashing into dad! I intentionally 'forgot' the outrigger at home, and it proved to be un-neccessary - the Sea Flea is quite stable, even in the hands of novice paddlers!
This one was completed as cheap- .....er, frugally, as the first. Paddles and sprayskirt are also dad-made. I have posted several build pics in a thread at the link included....