Unless you are doing the design work for the experience of it, there are several designs for smaller kayakers already available. you could pick one of them.

For a 6 year old, you have to remember that by the time a stripper is finished the kid will be 7 or 8, and the boat will probably survive until they are 26 -- or older -- so be generous with the sie of the thing. Kids WILL grow into a larger boat.

If you would like, I'd be happy to send you the plans for the "Skimmer" a 11 1/2 foot plywood kayak which can be built rather quickly. It is built from 1/4 inch exterior plywood assembled over a frame of forms and chines. it does nto require fiberglass or epoxy resin, (unless you want to use the resin as awaterproof glue) so it is inexpensive, too. It is a good size for teenagers, and if you want to scale it down for someone younger, that should be rather easy to do with a pencil and graph paper. I'd keep the length about the same and make the boat narrower. I've scanned the two pages from an out-of-copyright book and they can be e-mailed, so there is no charge -- not even postage!

e-mail me directly if you are interested in looking at these plans.

Another option is to build her a skin-on-frame design. There are some designs taken from the lines of authentic native craft, some of which were rather small by modern standards. If you think the skins are too fragile, build the frame to specs, and cover it with 1/8th inch plywood.

Using an existing design you'll get your project off the ground a bit faster, and get your daughter out on the waves a bit sooner.

PGJ