I wanted to get some advice please for regraining/cleaning larger pieces of metal for playfields. I will include a photo below of the pieces etc. Its mostly all too big for a tumbler, and even then, I dont think a tumbler will cut it if a wire wheel at high speed wont even cut the mustard.

Alot of the ball marks are very difficult to get out of the metal guides that the ball often flys thru. I have used a wire wheel on a drill before, but these metal bits are proving impossible to clean and get the marks out. I have used a very harsh wire wheel on a high speed drill, and have used Beakys bench grinder , again with avery very rough wire wheel, but the metal is just proving EXTREMELY hard, almost impossible to get the metal refinished to a decent level.

Just to clean one side of one large piece took at least 20 minutes, non stop. And the other side, which I want to clean properly will not work on a bench grinder/wheel etc.

* I was thinking commercial sand blasting the metal (but not too commercial so it stays undamaged etc OR even looking at having the metal acid dipped/cleaned/restripped that way.

Any advice, cause the wire wheel etc will not cut it on this set of very porous metal. Any help would be appreciated before I head off to sand blaster or acid dip land !