After watcing the precious plastic videos:
“Create precious jewellery from shredded CD CASES”
“Precious Plastic – How to finish objects from recycled plastic”
I saw that the only plastic types that were workted with and sanded was PS, PP, and ABS. As all 3 are fairly hard, and obtains a nice finish. But i wanted to see if you could get the same results with the pretty soft plastic HDPE.
I will be using wet sanding paper with P400 P600 P1000 P1500 P2000 P2500
Watch how this ring transforms:
0
Before:
The ring is cut in a basic shape with a knife
If you have a produkt made with injection or compression, you might want to skip some of the first sandings, but as the knife has left the ring pretty rough, i have to start with P400
@anris already saw and very impressive also… And comment from your girlfriend?
And you did you saw my post? http://onearmy.world/community/forums/topic/share-our-creation-%f0%9f%8d%8e/
Nobody answered
I will extend the delay…
No problem @dbougas i am glad you like it! 
If this was interesting, then try and jump by this topic:
http://onearmy.world/community/forums/topic/plastic-presents-merry-xmas/
Were another ring is made + plastic pearls for a bracelet
– All the best, Mathias
Hi how it is possible that I miss this perfect post… Thanks a lot
DiB
Hey @clementhempel thanks for the comment but i have had no problem with heat, the rotary tools or the surface getting ruined.
Sure the rock gets a bit warm, but when taking a few seconds brake once in a while, no harm should be done.
But i noticed that you should be rather carefull about the plastic particles that are created in the process, dont get them in your eyes or mouth and remember to colleckt them when being done with the sanding.
I would be careful with rotary tools as they build up quite a lot of heat, which would in turn absolutely ruin the surface finish
Sanding with machine:
Tried to sand the HDPE with a machine as @pe-trhlinka suggested.
– I attached the rough unfinished ring with tape to the grinding tool and gave it a go with the wet sanding paper (A mistake)
– With the high speeds, the plastic ring didnt get sanded at all, but would scratch off the “sand” from the papir.
– Went with a rock instead, and the results were much better.
Remember safety, i dont care how you look, just remember to projekt your eyes and mouth when sanding plastic at high speeds inside (i found some 3D glasses and mouth projektion, wich worked for me)
Uploading the last pictures of the final result, to show, from different angles, just how smooth it got.
It surprised me how prescious you can make the material, just by working with it, instead of throwing it out.
– and how much it looks like a brand new material or some rare rock
Wet Sanding plastic:
If choosing to go with the machine-based sanding method suggested by @pe-trhlinka
or if you are going to sand alot of material off the ring.
Then make sure you change the water often, or make some sort of running water system.
I experienced alot of plastic bits swimming around in the water after a bit of sanding.
With no prof, I am still pretty sure it slows down the sanding process with all these partikels going around.
the sanding is faster with this but the ring has to be round, that is the only disadvantage I think, when I made my first wooden ring I also didn´t sand it with this method 
the second ring was much, much better
Thanks @pe-trhlinka !
Took me about 60 min to sand it by hand, while also taking pictures and changing water
Great video! i cant believe i did not think of that before, even though i have all the ingredients to make it happen.
I have to make another ring with that method.
I gues it will save me at least 40 min 
looks great! thank you for your input, how long did you sand the ring? quick way how to sand round rings can be seen in thes video: ring sanding
P2500:
I went for the last paper just to see what would happen, and the ring is just super shiny at this point. If you are wondering if you should sand HDPE i can conclude, that you should totally go for it!
P2000:
The ring is essencialy done at this point, super smooth and nice to touch, and it starts reflecting the light. If you want to save time and money on sanding paper, just stop here.
P1500:
My optimism for the experiment starts rising, as the plastic looks fairly nice at this point. You can still see small scratches from the sanding paper, that i think will be gone with P2000
P1000:
The white cloudy spots starts fading from the ring
along with the last edges that should be left.
P600:
This time the plastic gets even more cloudy and white, but it also starts feeling nice when touching, as allmost all of the edges are gone at this point.
