This is my very old program that helps manage your Garry's Mod Source SDK mapping with ease (It also includes FrontEnd GUI Workshop Tool). This old program will require Visual Basic 6 RunTime to be installed (Redists are included).
Please note that use at your own risk! This program will not provide any guarantees and is no longer updated/maintained. Use for Legacy purposes only! (though, I'm still using it for Garry's Mod mapping anyway)