1. Vacuum Assisted Casting

2. PU resin selection Polyurathene resin usually available as a two-part liquid set Cured resin can be  As soft as rubber  As hard as ABS  As clear as Acrylic  As heat-resistant as PC  Filled with copper powder or glass fiber

3. Colouring of PU resin Natural PU resins are usually black, white, ivory, or transparent White or transparent can be dyed by acrylic paint or model paint All hard PU can be primed and spray painted

4. Vacuum PU casting machine

5. Automatic and manual casting Automatic and manual machine work on the same principle Automatic machine can degas, mix, pour, and re-pressurise according to pre- programmed timing

6. Casting setup

7. PU Curing Curing temperature  Heat can accelerate PU curing, ideally newly cast PU should be transfer to oven set to about 50 deg. C  some PU will not even cure in room temperature De-mould time  Range from 5 min. to 30 min. Cure time  Time to reach optimum strength  Range from 30 min. to 12 hr.

8. Post-processing issues Cut away the runner by saw or cutter Wash in warm water to remove trace of chemical on the surface Hard resin can be machined, filed, and sanded Primed and spray painted like ordinary plastic prototypes