Okay, can I make a thread shop for art about making trails for people?
I was planning to do a trail texture shop that people pay 2k for custom trails, while they fill out a request form.
Is that okay?

It should be fine. If you do it in Art/textures forum, I think it is allowed.

Everything is allowed as long as market rules are not broken. It's just like a request shop, which is allowed.

I also suggest having a quick view at market rules if you haven't done already.

well many people open requests like that, and you are a senior member, why you still ask about it?

Well, I seen some request shops get closed, just wanted to make sure.

Request shops get closed because they have not followed the rules. Be sure to read the rules for a full understanding.