I like Rick's idea the best, and wish I had drawn my own complete plans from the beginning. I started with a set of plans from Waverly Street. I did not like the shape for some reason, so I modified it a little, enlarging the lower bout. I was starting with almost zero knowledge of instrument building, and it seemed like a pretty tall order to understand all the things going on in building a nice instrument. Aside from the soprano plans from the Grellier site, maybe the Martin plans from GAL, and who knows I have not seen the plans from Hana Lima, I suspect that the 'best' designs, for a nice uke are in peoples own possession, their own designs. It is a lot to understand, starting from zero, to draft a complete instrument with well designed 'relationships' among all the parts, but, if one follows a plan all the way to completion, afterwards, all the knowledge needs to be absorbed to a small degree, somehow by the end of the process anyway, so why not start at the design stage. I am still very much a beginner builder, but I see now that making your own design is not too much for those who are inclined, and IMO, a great way to study instrument making. There is information on ther internet about using 'Divine Proportion' in guitar body design, Beau Hannam posted a link to a video or 2 on this subject. This helps with guidance in deciding the width at the upper bout, waist, lower bout, bridge location, length of body, etc. Choosing the size and scale length (Soprano, Concert, Tenor, Baritone) then choosing how many frets to the body, 12 or 14, how many total frets. Deciding on a headstock angle, choosing a neck/ body joint method (bolt on?) Choosing the thickness of the neck only at the 1st fret, and 10th fret (neck thickness/ taper) Choosing the neck angle (flat works) and headstock angle, style of headstock. ( Choosing the radius of the back and front (research necessary) Choosing you bracing style. Deciding on a fretboard thickness, and bridge/ saddle thickness. Body depth at the tail and at the neck join. Making a drawing is important. In my own experience, I heard those words, and could understand their importance, but 'closing the gap' was still difficult. Having a set of plans nearby to refer to , conceptually, is helpful. Look at photos of nice ukes, and even better, at nice ukes in your hands. In another current thread, there are photos of an assymetrical ukulele built without a mold. (just mentioning this for the concept) With most any plan, unless you are building a kit, you might also be considering building molds, or a solera, and possibly/ probably, other fixtures/ jigs. I still have the set of Waverly plans, and a matching mold, some other jigs I made for that build, I am ready to pass them on to someone. Flexible drawing edges are available for drafting your design, French Curves are available, choosing a fully rounded lower bout, or a lower bout with a flat at the tail, a little flat for the neck joint, or a round upper bout, if you draft your own, you get to make your own choice.
Drafting your own design is not too difficult, and the learning process is fun... Many people on this forum can easily answer questions on the 'how, what, whys' of design. Dig deep and enjoy!