The aluminum profile on my large CNC is 80/20 series 10 (1″ x 3″). I got it from 80/20’s store on Ebay. The store name is 8020inc.
If I were do it again I would use a larger profile like the 15 series or the 10 series in 2″ X 4″ inch size.
The KR33 CNC uses the same series 10 profile but it’s 2″ x 2″ in size.