How to reduce stretch from Pueblo leather (1mm or less) for card slots?

[Aaaron]

Hey there! May I ask how does one make card slots out of Pueblo leather? (Especially if it has been thinned to 1mm or less) I recently worked with Pueblo leather for the card slots of my wallet and it stretches a lot more as compared to other leathers. Was wondering how do y’all make Pueblo leather card slots without it stretching too much? It gets difficult to work with when it is flimsy and stretchy too :/. (Attached photo is taken off the web as reference )

[battlemunky]

I have some 3-3.5 oz I use for wallets and haven't had any issues. I'm not sure how thin yours is. I do notice it being more supple with a softer temper to it than regular veg tan but it behaves pretty close to it.