Diamond Sandpaper
Supose you want part of your hold smooth? You can use 50-70 grit flexible diamond sandpaper to sand down synrock like it is wood.

Of course you could also do that with a plastic hold, but it would feel like a smooth piece of plastic, not a smooth piece of rock.

And with synrock, you can go the other way as well. Sand it down too smooth for your taste? Just acid-etch the hold again.

When you get familiar with the process you can dial in a texture that is absolutely amazing.

The best texture you've ever climbed on.
Where to get diamond sandpaper?

Use these keywords, (diamond sandpaper hand pads) in a search engine such as google and you'll have lots of options.