My 123 blocks from my machine shop days get lots of uses when assembling buildings. I have found that clamps for the most part work better then the magnets. But I do us magnets also. On of the other things I find very useful is a small work surface that I built that is just a 12/12 piece of 1/2 MDF covered in tin, with 2 pieces of 1 inch aluminum angle iron screwed to it at exactly 90 Degrees. I covered the surface with tin so help keep the glue from sticking. The jig and two 123 blocks makes is childs play when assembling buildings and the like.
Digid