Gene, it may be. I'm not sure though. Back when I used to replace the flat leather belts on lathes and such, we used a similar approach, We layed one side of the belt down and then folded the other back onto it, with the top end about three inches back from the bottom one. We then sanded a taper on the belts untill there was fresh material along the length of the sanding. Some hide glue on the joint and clamp it between a couple boards with some wax paper between the boards and the leather and let it set for a couple days. WaLa a new belt. Not much call for that today. The basics are the same though. The more surface area you can glue, the stronger the joint. If you look at some of the wood trim in the lumber yards today, they are made up of finger joint stock, several long V's cut to incrase the glue surface. It is very strong because of the extra surface, and the fact that there isn't a single plane that can be stressed to cause the joint to fail. A 45 degree cut like I suggested will fail if the bend is 45 degrees to the length of the sheet. It is quite strong if the bend is across the sheet

MinFlyer, a lap is not the L shape, but the description above of the belt lap joints. IE one sheet laps over the other. Getting the lap angle right is very difficult on something like a 1/8" sheet of 3" wide balsa. If the angles are not dead on, you end up with a very weak joint. To get this joint to work, you would need to lay out the sheets like I described for the leather belt. one over the other Then the sanding would need to be done by sanding in only one direction so there isn't a bow in the surface, it has to be dead flat. Then the second issue come up, the sanding line also has to be at exactly 90 degrees to the length of the sheet, otherwise you will have an angle in the joing if you have full contact, or only have a narrow contact along one edge. It is a very difficult joint to make in thin stock without some accurat jiging for the surface preperation. The 45 cut is the best as you have less room for error. You still need to keep the cut 90 degrees to the surface though.

Don