[TmpstsTrrctta]

+1 for rails like these. I’ve used 10 series aluminum extrusions in a roof rack, roof top tent, awning and solar panel setup. I purchased all mine and accessories from here

https://www.tnutz.com/product-category/10-series-extrusions/

[082349872349872]

Incidentally, as a kid I loved Fischertechnik kits; they're like Lego but instead of a brick as the basic element, they have X-linear rails.