This is a really great proposal for the future of JCS. Self-made tilesets around a certain level will allow aspiring level designers to truly let their creativity run wild, by taking away the limitations of the tileset they choose to use for their levels. By creating own tiles rather than resistricting themselves to the possibilities of a pre-prepared tileset, people have the freedom to "whatever the heck they want". We could be seeing truly creative and wacky ideas being born, allowing for original looks going beyond fancy use of Layer 4 tiles in the background. Plus, like FS already mentioned, tiles can made designed specifically to work around a concept in an individual level, allowing for yet even more possibilities.

I'm basically saying I approve of this 100%, and will be willing to help out with this project in any way possible.