To make avatar items in Roblox, start by creating the asset using tools like Blender or Maya. Ensure your 3D cosmetic item is centered at position (0, 0, 0) before exporting.
Next, export the asset as an OBJ file and import it into Roblox Studio. Be careful to import all parts correctly to avoid issues later on.
After importing, use the Rig Builder in Roblox Studio to align the asset correctly. Make sure it is positioned and aligned well with the avatar for a seamless look.
Then, use tools like meta balls in Blender to shape and refine the asset. Add any desired details and features to make your item unique and appealing.
Finally, convert the asset into a UGC item using the Asset Creator plugin. Create a thumbnail with the UGC Thumbnail Tool and upload it to Roblox, following the guidelines for UGC creators. If you wish to sell the item in your game, enable it for sale using the Creator Dashboard.
By following these steps, you can create and sell avatar items in Roblox.