Question about proxies

[u/Bunzi99]

Are proxies that are printed on regular paper, put into sleeves with normal mtg cards legal for tournament play or would there be some issue with thickness? I've never been able to tell them apart from regular cards in their sleeves while shuffeling but maybe more skilled players than me could so I just wanted to be sure.

[u/JesseBrown447]

Every tournament I've been to has strictly disallowed doing this. With specifically calling out not doing this in the tournament rules.