Today’s invention is a new form of sanding block.
I hate rubbing down before painting…so boring, yet so necessary.
If you are making some product with a fine surface finish, this preparation is even more important.
Imagine a block made of highly-compressed sandpaper sheets. The top few sheets could be made of ultra fine-grade abrasive particles. Lower layers would be made of progressively coarser ones -giving greater uniformity of the final surface texture.
The glue holding the sheets together would be made in different colours.
This would rub off a little onto the workpiece, so that you would be able to tell where the highspots currently were and also when it was time to swap to a new block.
Maybe this is a real-world application for additive manufacture…just feed in a liquid whose abrasive particle content varies with time.