Guys, some log to recommend me?

As you see im looking for something useful, i was thinking abt use UPN because are not hard to find in Argentina at normal prices (i pay 18USD for 1 meter of used UPN 160mm yesterday).
Companies that cut aluminium and steel with water/plasma/laser are very expensive, but looks like i will need to pay for that service.

I get the idea of use UPN because its used in some of the vids that i post, but of course they guys have good welding equipment and mill the welded surfaces to fix deformations.

Im a little lost now... EPOXY very expensive, machining very expensive.....