Stencils

Stencils are sharable collections of objects just like Geometry Dash's in-game "Custom Objects"

The basic format for stencils is the exact same as custom objects stored in your save file. You can use them with a mod like BetterEdit 4 to paste in the object string. Other formats are supported too but may have limited support.

Uploads are only enabled for select beta testers.

You can get level strings from your save file. There may be mods that can help with this.