Overly stout because I designed them as feet for an heavy printer enclosure. These end caps are where designed for Misumi 6 Series, Base 30 extrusions but should work on any 30mm x 30mm or 30mm x 60mm aluminum extrusions.

Based on caps by ZINN0711 but remade to be easier to print and unnecessary thickness. Making the extrusion end surface flat gave me more area to glue which was important to me.