I use the plastic hinges that have a removeable pin.
Pull the pins out of the hinges and run a LONG piece of stiff pushrod wire thru all the hinges on 1 surface. Take a straightedge long enough to make a line the length of the surface. Put the pencil down and start pushing slots along the straight edge in the locations. Make the slots way to wide for EASY slide ins later. DO NOT WORRY if the slot is angled up or down a lot. The hinge will automatically take care of it. ************DO NOT TWIST the slot cuts.************* That WILL BIND any hinge. This is where a WIDE Exacto blade helps keep all the slots from twisting.

I use a metal straight edge and using enough foam rubber around the control surface, put it into a vice or clamp it between 2 pieces of wood to steady it while working. Nothing is able to move except the straight edge and Exacto blade.

I sometimes use clear tape to hold the straight edge steady and just poke the blade up and down.

Easier to do than write.

The long wire holds all the 1/2 hinges in perfect alingment while the 30 minute Epoxy sets up. I stuff a TINY bit of glue into all the slots first. WHY. As the REAL hinge 1/2's are pushed in, NO GLUE can slide towards the exposed hinge pin holes.

You DID PRE VASALINE the hinge joint edge of the hinges ????

Repeat the mating 1/2 surface the same way.

It really is foolproof.