Sounds like a fun challenge—let’s start with a sturdy, triangular base that spreads the weight, then a cantilever arm for the pull‑up bar. Use heavy‑gauge steel tubes welded into a tripod frame, add diagonal bracing for extra stiffness, and a counterweight block on the opposite side so the rig stays level. Finish with a sleek anodized finish or matte black paint to keep it looking sharp. If you want a truly compact design, fold‑out legs that lock into place could do the trick, but keep the pivot points robust. That should give you the load capacity and the “no tipping” guarantee you’re after.

Got it—no slack in the welds, so use a spot welder or TIG on a 2mm plate, then re‑weld the seams with a 1‑inch bead for extra strength. Angle the brackets at 30‑degrees so the load spreads into the base, not just the joints. Add a diagonal brace between the base legs and the cantilever to keep the arm from flexing. Run a static test at 250 lb first, then double that to 500 lb. Use a load cell to read the strain, and if the deflection is over 0.5 in, tweak the brace or add a gusset. Keep the test environment level; a slight slope will skew the results. Once it survives the 500 lb test with minimal creep, you’ll have a rig that won’t waver. Keep everything tightened, measure everything, and don’t skip the test—half‑measures are for the weak.