I have a cheap chinese mill. At the time of purchase it cost around $700AUD shipped. Just a stock 2030 CNC. Of course out of the box it was missing a collet -_- (Couldn't mount tools) but since I also lacked a computer with a parallel port it was no great loss.

Fast track a few more months, I had invested the cost of mill on a new spindle, new control board (TinyG) and a quaility selection of 6 end mills. 2x 3.2mm, 2x 1mm, 2x 0.4mm.

Above is the shot of the final details being cut into a mold. In this case a carridgePlate. This part will eventually be bolted to 4 openbuilds v wheels and form one of my linear carridges.

The resin casting process is quite simple. Make a positive mold of your part. Cast a negative using a flexible material, silicone. Finally fill this negative mold with polyurethane resin then remove your hard plastic part. Easy.

Here is a shot of the cnc'd mold. The silicone negative and then finally the cast part. In this case this is a 2 part mold, the two halves are held together while the polyurethane sets then they are ten apart to release the part.

Close up shot of the detail that can re resolved using this technique.