I don't have experience leatherworking, but DEFINITELY have experience in struggling to just tell people no. And logically, I understand that saying no would lower the volume of requests you're seeing. To me, it's not about saying no to be mean, but about setting clear expectations and boundaries in a non threatening way.

Maybe a dedicated website explaining your prices and policy, with an acknowledgement that you appreciate the support from your friends but can't afford to take on every single project they suggest. This would give you a way to redirect people to your explanation in a format they're less likely to push back on. Most people will be understanding of this, giving you more emotional bandwidth to deal with anyone who is pushier about their demands on your time.

If there are standard pieces you'd like to offer, you could list them here too, giving your friends a specific way to channel their support while still being manageable for yourself

Regardless of how you proceed, I wish you luck and strength my friend. Leatherwork requires skill and it sounds like you've found a fun hobby to pursue.