Fixm- Thanks- It is comments like that, that make it worth my time.
Aajenki- Not usually. Using the pins method on tiny pieces that are not under much stress is a lot of trouble. For the boxes, I often just use Weldon #16 on one piece, then mate them together and put a weight on it. I make sure that the #16 oozes out both sides of the seam, and dries with a full fillet on both sides. Then I flush trim the outside away.
For the tube to box and tube to flange joints, I cut a 1/8" groove in the sheet material that is a snug fit to the tube. I fill it 1/2 full of Weldon #4, and wait about 1 minute. Then I drop the tube in to place, into the softened groove and put a weight on the top of the tube. This makes a very strong joint, that does not ooze out extra so it looks very clean.
Cutting the groove is a pain. I use a fly cutter in the drill press that has been carefully ground to the right size. I also use a vacuum clamp fixture to hold the flanges to the table of the drill press (actually a mill, but it acts like a drill in this case). Without a vacuum pump, you can use any kind of clamps that will work. I have even temporarily put wood screws though the "thumb-screw" holes to hold the flange in place while I cut the grooves (O-ring on one side, and Tube on the other). I cut out the middle of them last, as I need the 1/4" pilot hole in the middle for the fly cutters.
Sound clear?
Zeph