Of course I have to chime in.
I built a 11' Yost Sea Flea with my daughters. It served them very well, and cost me about $120 to build. It would have cost less had I used spruce lumber for the frame rather than cedar. I would guess that is was about 40 hours to build, spread over about 6 weeks of occasional evenings and Saturday afternoons. Certainly much easier, cheaper & faster to build than my wife's cedar-strip.
You can browse through my build journal and related posts using the label "kid kayak" or click here
http://pawistik.blogspot.ca/search/label/kid%20kayak
http://yostwerks.com/SeaFlea1.html
Using PVC-coated fabric, bought from one of the local tarp/awning manufacturers here in Saskatoon, the skinning was fairly easy using staples and glue - no sewing required.
I also created a simple removable outrigger. Next time I'd place that a foot or so farther back where it is more out of the way of the paddle stroke.
Float bags using the same PVC-coated fabric fore and aft provide floatation. We towed the kids more than they actually paddled; thankfully, it tows very easily. It fit the girls from about age 5 - 8. When my oldest was about 8, I moved her into the Tsunami SP, which I can also highly recommend. Now that the younger daughter is outgrowing the Sea Flea, I have ordered a WS Focus 145 (new model for next year) 14'6" x 22.5" kayak for the older daughter to paddle (she'll be nearly 12 by the time she gets to paddle it). She would have fit the Tsunami SP for another year or two, but the younger sister (currently 8 ) is outgrowing the Sea Flea the younger girl is bumping her older sister up to the next kayak and inheriting the Tsunami SP.
For those that build a Sea Flea, I would encourage you to make the opening in the station that the legs pass through as large as possible. That will make getting in and out easier. In fact, that is the only reason my daughters outgrew the kayak. In fact, I think I'd raise the deck height about an inch at that station, and replace the top of the station with a horizontal piece of plywood. (Thinking through the text here, a station in this location in the form of a plywood box would likely work well, reinforced with fiberglass.) You can see the stations and structure of the kayak in the photo below, taken before the deck was installed. The bow is to the top of the photo and the minicell foam is the foot rest.
And, if you want to have a look at a Sea Flea in person, or even borrow one, I know where you can do so.
Cheers,
Bryan
(
After all that you may wonder why I didn't build the larger kayak - e.g. Sea Pup - for my growing daughters. Time, space and time. Even a quick build like these takes some time and I just don't have much of that, it seems.)