"What's the Sandbox Menu?" You might ask.
The Sandbox Menu let's you spawn any weapon, enemy and item in the game and it's the only way to get Workshop weapons

I know the game doesn't run well for now but you need a computer that has the minium or recomended specs required.

Doesn't matter if you have a laptop keyboard, 90's desktop keyboard or a Razer Chroma 420 v69, follow the instructions bellow:
If you have a QWERTY keyboard this is easy because P is located to the right of the letter O.
If you have AZERTY keyboard or use a different language besides English, tough ♥♥♥♥ IDK where it is, use your eyeballs and locate the PEE.

Buy the game on Steam.
If you somehow have this game through illegal ways, tough ♥♥♥♥ this ain't going to work. You need a legal copy.

This is self explainatory why am I even ty-

Doesn't matter if it's a Story map, Endless or from the Workshop, it just works in any map.

I know what you're thinking "but I know how to press P".
NO.
YOU DON'T.
You probably tap P like how I [CENSORED JUVENILE JOKE DUE TO BEING UNFUNNY].
You need to gently press P, like the gentle and fine lad you are. Treat it like a beatiful lady and be gentle with it.
[Author's Note: I didn't want this last part to sound weird but it's too late now, ♥♥♥♥ I hate this]

CONGRATU ♥♥♥♥♥♥♥ LATIONS, YOU OPENED THE SANDBOX MENU, NOW SPAWN EVERYTHING AND MAKE YOUR GAME CRASH AND PROBABLY EXPLODE YOUR COMPUTER. HAVE FUN.