Scuba Steve let us know about his newly created resource site, The Weapons Emporium :
It's a place where I will showcase all the weapons I have drawn for DooM, and where you can freely take any gfx you see for your conversion. There's no asking for permission (unless otherwise noted) because I am making all these guns open to the public and free to download. I will also, on occasion, take a request or 2 for creating a new weapon.
No need to say Steve really deserves a big thank you for his time and efforts.