Guides for creating your own Workshop mods can be found here.
Creating Characters / Player Models
https://towerunite.com/guides/wk_creatingcharacters_v3.html
Creating Items
https://towerunite.com/guides/wk_creatingitems.html
Creating Vehicles
https://towerunite.com/guides/wk_creatingvehicles.html
Creating Sound Packs
https://towerunite.com/guides/wk_creatingsoundpacks.html
Minigolf Map Creation
https://towerunite.com/guides/wk_minigolf.html
Ball Race Map Creation
https://towerunite.com/guides/wk_ballrace.html
Zombie Massacre Map Creation
https://towerunite.com/guides/wk_zombiemassacre.html