last weekend I printed three Marvins: 1x Bronzefill, 1x Brassfill and 1x Copperfill. After printing they were pre-polished for approx. 8 hours in my self designed rocktumbler and finished with a buff wheel. Not perfect yet, but the result is ok for a first try
The lesson I have learned is that I have to print finer layers to make polishing easier - will try it soon.
I used brass screws, works fine.
Unfortunately your message regarding the ceramic pyramids came a little bit too late: Yesterday I ordered exactly this kind of grinding “tools” to experiment with it
I’m just assuming it was a typo when the word ‘full’ was used. Perhaps it was meant to be an ‘i’ and not a ‘u’. Will be posting a truly fUll metal Marvin in stainless steel soon ; )