The GunLine scraper outer will work for most stock materials, like wood, laminated wood, plastics, fiberglass/plastics, carbon fibers. Hardened steel disks with pointy sharp corners. Disks separated by rubber washers that allow disk corners to flex & bite into surface. Never tried it on aluminum, might work on removing small amounts but would dull tool quick.
Scraping with grain makes for a smooth level surface & is much faster than sanding, like removal of 1/8 of wood.
I have several scrapers that I made from files, and I use them for tight places & detail work. They don't look as nice as the Jerry Fisher scrapers but are cheaper & sturdy. A bench grinder & diamond stone will make these. If no barrel channel, like flat, drawing a line thru the middle of work then carefully drilling out wood with a line of holes carefully not too deep, then round wood rasp, then scraping makes for the fastest with hand tools.