Flat Surfaces and Perpendicular Bends for ease of mounting/accessorizing.
Ideally forged C-frame, but can be welded in a pinch. Tapped hole on one end and machined flat on other end.
Acme thread with stopper on one end and hole with pin on the other end. Pin has bulge on ends (either tack weld or hammerdown)
Linear guide: angle welded on a C-Clamp face. Angle drilled and tapped for bolt. Angles acts as single-side linear guide, bolt compresses material.