There are many nesting dinghy designs; they come in 2- and 3-part hull designs and a web search will give you much to choose from.
Having built and used one, I think it's worth carefully considering how the two (or three) hulls are joined when you're in the water and everything is bouncing around; the 'mating' and 'disconnecting' events can be difficult in anything other than placid conditions.
Also, don't overlook the height a nested dinghy will take on deck. They typically are more of an obstruction to forward viz than a single-hulled hard dink, and you may need to consider boom clearance as well.
A final cavaet: Most of these designs use thin plywood with reinforced gunwales, corners and thwarts, and with the ply sections being epoxy coated. In truth, a ply dink can take quite a beating out on unimproved parts of the cruising trail; they are not as robust as a GRP lay-up...nor as easily repaired. If to offset this, you cover the ply with a layer of GRP, the weight goes up and one piece of a nesting hull may weigh what a full-length GRP dink weighs. Just one of the trade-offs worth thinking about; for local or 'easy' cruising this is not a big issue.
FWIW one of the successful recent nesting dink projects, well documented and with a savvy guy to follow up with Q's, is Terry Sargeant's on VALHALLA. Look for it in his projects collection: http://www.yachtvalhalla.net/index1.htm
Good luck to you; it's a fun project.