After testing sand papering on clear resin (it take ages!), i discover a fantastic way of doing things much more properly and much more rapidely. I take steel wool ( we call it like that in France anyway). I take quite a long bit of that steel wool in it’s finest grain ( 00 ) and fold it to get what we call in foundry an elicopter when it is set on an iron axis on the drill. I then fix the drill tight on the bench and making it turn not to fast and i gently move my Print to the wool. It removes scratch whithout leaving marks. Then you just have to spray novus or minéral oil to get a very clear looking resin. Hope it helps!
Thank you @Gantelet_Stephane, I shall definitely be trying this. We (in the netherlands) call it steel wool as well :P.
Alex
Could you post a photo of how you built this? And the results? Very interesting. I’m sanding some pieces and takes freaking forever.
Thanks.
@Gantelet_Stephane, thanks for a great tip!
I’ve got lots of steel wool that I use for woodworking… Never thought of using it to finish plastic parts 
Thanks.
Here more details whith photos as Victor asked.
First i must say the steel wool trick is good on 25 microns printing. To get read of the structure marks it on the print or print step marks if your print is above 25 microns (50 or 100) i first use the hélicopter technic on a 500 grain sand paper. I cut a long piece (1.5 cm large) of it and then fold it in less than 5 cm bits.
Whith a nail and a hammer i make a hole in the middle so i can drive my dremel like axis in.
Then i cut the fold eges so each of the bits of sand paper ar free from each other and organise them so they overlap but cover the whole permiter around the axis.
That make a circle of around 8 bits of sand paper. This is absolutely great for uneven surfaces if for exemple like me you have bumps or texture on your print you whant to avaoid paking flat but still need to sand paper them. Because the paper arange this way is very flexible it can do that for you. You must not have it turn too fast as it will ruin the paper very fast and tend to be to agressive. If you do it gently you can sand paper this way very delicate parts.
The paper tend to twist after a while and become more flexible. This is the time to go and do the job in deep cavity on your model. You could imagine use the same technic whith 120 grain corindon paper if you want to smooth very rapidely a lage surface that suffer from deep marks before doing it with 500 grain paper.
Once this is done i do exactly the same thing but whith 000 steel wool. I cut a long bit of 60 cm but you can use longer.
I fold it (do not cut the fold edges like on the sand paper) , make a hole in the middle whith a cisor and make it turn on my drill.
After a while the steel wool get pack oround the axis and if you put an enought long bit of it you will be able to sand paper your print putting a little pressure against the wool.
On that picture you can see that i am able to use the flexible accumulation of wool to go in small cavities.
And it’s done !
Another example on a textured surface (i mean textured in the model itself). I used ink and acrilic medium to emphasise the texture.
Sorry for my poor English but i’m French !
Hope it helps better.
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Awesome @Gantelet_Stephane, I tried this manually today and it worked really well.
Thanks again for the great tip
Really happy about that. Thanks for letting me know.
@Gantelet_Stephane, yes, we call it steel wool in the US too 
I agree that steel wool or scotch brite pads can be really useful for irregular surfaces (sandpaper is better for flats). Here is a useful chart for comparing steel wool grades to sandpaper grits. For example, 0 steel wool is approximately 100 grit while “4 0” (0000) steel wool is closer to 400 grit sandpaper. Scotchbrite pads are also useful for sanding (they are basically in between sandpaper and steel wool)
White Scotchbrite = 1200 grit (it has no abrasive)
Gray Scotchbrite = about 400 - 600
Maroon Scotchbrite = about 220-280
Green Scotchbrite = about 150 - 180
Interesting chart. Yes. Something else must be involved with resin because when i use 500 grain sand papier i’ve got some marks while 000 steel wool leave none ! I haven’t tried 0000. Must.
The problem with wool is the same thing that makes it good at smoothing irregular surfaces, it follows the surface. This makes it easier/faster to get a polished finish but it does not remove surface irregularities. You’re not knocking down the high spots, you’re simply grinding the surface down so it’s smoother.
The points where the supports break away from a print leave little “pucker” marks behind. High spots that need sanding down to get rid of. Also, aliasing of low-slope surfaces occurs at 0.1mm and 0.2mm, the surface has “stepped” features, like a 3D topographical map. You need sanding to get rid of these, too. Steel wool leaves a polished but rippled surface.
I used these to sand my prints. And also these other things…
Yes that does work but it tend to flaten the all surface. That’s good for untextured surfaces. But an hélicopter with 500 grain does the job of removing high contact points spots without flatening to much the surface. It’s not that agressive. Then you can use steel wool.
Thanks!
Be really careful with steel wool on a spinning mandrel. You can easily get small pieces in your eyes and even breath them in your lungs.
You should be able to get really nice results with an Air Eraser from Passche. It is basically a miniature sand blaster and will take off small build lines without destroying fine details.
Spraying into a plastic container will collect much of the grit.
Do a search for “Flap Sander” and you should get plenty of hits. I use a Dremel, their website has many choices. The foam sanding pads are 3M, you can find them at their website or your local Home Depot.
I tried your wire wool technique on a xbox 1 controller cover my son had been nagging me to print.
I just smoothed of the layer lines manually with the wire wool. It was very easy and I didn’t need to touch the part with sandpaper 
I printed it at 0.1mm and because the printer has issues the good surface wasn’t as good as it should have been. The internal surface is a lot worse 
Thanks again for the great tip!
We messed up the black inking as we used acrilic paint that dried really quick… live & learn.
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It looks really great. As KenCitron say it’s important to protect eyes and to wear a mask to protect you using a drill !
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