I swore duct tape was all a cardboard fort needed, then my kid's castle fell apart on day two
For years I built every fort with a hot glue gun and more duct tape than sense, and I figured that was just how it worked. Then last month my son and I made a castle out of four big moving boxes from the U-Haul on Broadway, and the whole thing slumped sideways by the second afternoon. What got me was that the flaps kept tearing right where the tape was stuck, so the walls could not hold any weight. A neighbor who does theater sets came by and said to stop taping the flaps and start cutting slots and tabs so the pieces lock into each other. We tried it on the next build, cutting a 2 inch tab on one flap and a matching slot on the other, and that thing held up for a week with two kids climbing on it. Now I keep a utility knife and a pencil next to the glue gun and I mark and cut before I stick anything. The tabs take maybe 15 extra minutes but the fort doesn't fold in half anymore. Has anyone tried adding a second layer at the corners, or does that make it too thick to slot together?