Several of the FT foam board designs use packing tape over the dihedral joint. The FT build videos show a tape dispenser that makes the process much easier than using the rolls of tape that you buy. This dispenser is weighted so you can tear a piece off with one hand. Here is a link to one that I bought on Amazon.
I made an easel from some PVC pipe. Works good for holding flat pieces like wings and control surfaces while painting. Used it to hold the wing on my FT Simple Scout while painting a scallop on the leading edge. One more thing, the FT brown foam board is water resistant, but the poster board turtle decks are not as far as I know. So it makes sense to paint them as well either with color or clear coat. Use some double sided tape to hold them to the cardboard while painting.
It could be that you want to add down thrust, right thrust, or both to a motor mount. I happen to have a 10″ disc sander that makes the job easy. Set the table for 3° down and the miter to 3° right. Sand off just enough from the front of the power pod, then glue the firewall in place. Of course you can make these measurements to suit your needs. Just recently bought a 5″ disc sander from Menards and I plan see if the smaller sander will allow me to do the same.
At a recent club event a friend was telling me about a fellow club member who was flying his model when suddenly the battery came loose and was just dangling from behind the motor. Something to avoid. My friends Bob and Ed were going flying and invited me along. My batteries were all charged but I was wondering if I have the velcro strap to keep the battery secure. Nope. So here is what I did to fix it. Had a few velcro straps from Flite Test, so I pulled out the power pod from the Old Speedster and cut a couple of holes for the strap to go through. Then replaced the power pod.
Already admitted that I am not good at free hand cutting the bevels on control surfaces. So instead I have been cutting off part of the foam board and replacing it with balsa. In this case I took a 3/16″x3/8″ strip and cut a 45° bevel on the table saw. So as shown below, the aileron is separate from the wing. Vertical and horizontal stabilizers work the same way. Then I use brown kraft tape to attach the pieces to one another for the control surface hinge.