M5 T-slot nut with washer and L 8 mm screws for aluminium

All t-slot systems are not the same! Which one you choose depends on your need for

T-Slot beams in a variety of profiles, from 20mm x 20mm to 45mm x 45mm See Wikipedia: 8020 framing systems · Another CNC machine? points out

three cherries slot machine T slot aluminum extrusion profiles are widely used in construction, transportation, machinery, chemical industry, electronics and electricity, shipbuilding,

today slot T-slot structural framing is a framing system consisting of lengths of square or rectangular extruded aluminium, typically 6105-T5 aluminium alloy,