This is a scaled down version of the RCM 60 size floats, scaled to 66% for 15 to 20 size planes.
An alternate version is available with a 1/2″ x 10 inch spine to take the place of the plywood brackets. This spine is to be glued on top of the float. Your landing gear axles are then attached with nylon straps. Please specify which version you want.
These can be built without a plan. Attach the bulkheads to the float tops, using the laser etched marks as a guide. Add the sides and longerons, then the bottom sheeting.