Subject says it all. I don't need to make the chalk but just the actual way to buy it but I'm unsure on how to do that. Any help is greatly appreciated

You can put the xmodel that came with the gun, on some wall. Then put a trigger>use. Then select the trigger and hit n on your keyboard. After that type this

targetname
zombie_weapon_upgrade

hit enter and then type this

zombie_weapon_upgrade
(name of your gun(the name is the exact as the name weapon file))