Should I stay with powder-coating and if so how can I prep my material better?

I'm building electronic devices into pedals made out of cast aluminium material. They come with black powder which I strip using sand blasting. After the blasting the parts are coated with a chrome-like powder. The problem is that we have to use OGF powder in order to minimize the bubbles as preheating does not help (cheap material). Another problem is that the surface is not smooth after the blasting so the finish is not mirror-like as much I would want it to be. I was wondering if putting the boxes in a tumbler would polish them up well enough so the coating would look better. another question is, do I need a primer coat before the chrome (like a satin black or something similar).

The last question is should I even stay with powder coating? I wanted to use real chrome plating but found out that no one wants to coat cast material from all kind of reasons.
I'll greatly appreciate any help on this topic.

Depending on what alloy it is, it may be possible to chemically strip the paint and bright dip and anodize the pedal. Maybe (but not likely). It can be chrome plated, and this could be a premium finish if done well. Virtually all chrome plated automobile wheels these days are pressure cast aluminum.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

The material is very cheap, I think it's made of left over metals and mostly aluminium. The surface of the part is not totally smooth to begin with and that's why the factory uses a heavy epoxy-powder to coat it but the finish I need needs a smooth surface.