Here were is a guide of sorts to how I polish my acrylic block tops.
In this pic you see the machine marks that we need to get rid of. They are on the inside of the block only. They must be removed to have glass like clarity at the polishing stage.
First you use a heat gun on the EK badge. Get it nice and hot but don't melt the acrylic
. If you are not going to reinstall the EK badge you will need to sand the recessed circle at each stage.
Start w/ 400g on the bottom of the block. Use a piece of glass to make sure you are sanding flat when you are doing the bottom. You don't want an uneven sand job and possibly get a leak. For the flat part of the bottom you will want to sand in two different directions. You don't need a lot of 400g. You will also need to use 400g on the inside machined areas where the coolant flows.
Then move up to 800g. You can do the tops and side w/ this grit as well. Not too much pressure on the top though as you want to maintain the circles and print. By the end of 800g all tool marks should be gone. Once again sand in the coolant channels. Make sure to get the edges.
Move up to 1000g. Do the entire block just like above.
Rinse and repeat w/ 1500g (if possible) and 2000g. Should look similar to this at the end of 2000g.
Now the polish. Use a good acrylic / plastic polish. Not a metal polish. It will cut polishing time by 10x. I use Meguiar's PlastX. You'll need some good polishing cloths too. Old t-shirts work.
Now go to town on the polishing. Use a liberal amount. First polish w/ a wet part of the clock (wet from polish). Then move to a clean part and polish dry. Do clean in the threaded parts add polish to the threads and corkscrew in a cloth.