I reinforce with bubble gum, preferably double bubble really though the airframe is supposed to be light and I would just look for those places that seem weak and reinforce them only. I have also used polyurethane glue very sparingly because it will foam up and attach itself to anything. Slightly dampen the area and then apply a little poy-u with a tooth pick and let it do it's magic. I like to use nylon bolts for landing gear so they shear off instead of taking the whole bottom out.