hot-glue your mold into an (laser-cut) acrylic box.
Spray mold release onto parts, do two+ applications, 5 minutes apart, wait 30 minutes to fully dry, you can brush on the release as well.
Prepare Space; place wax paper on floor and surfaces.
Pre-Stir/Mix (by hand then use drill turbine) Epoxacast "A" Resin for several minutes each; Mix "A" (100 units) to "B" Hardener (8 units). Pour molds (using funnels). Measure by WEIGHT not by volume.
Let it set for 24 hours; heat cure in toaster oven two hours at 175F; then three hours at 300F
3D Printing Observations
Objet resin prints did not set correctly, possbily not enough mold release, or possibly due to objet verowhite plus reacting with epoxacast materials. I would recommend adding the extra step of a silicone mold.
3D Printed ABS filament was vapor polished- by heating hardware store Acetone (some nail polish removers have additives that don't work well) inside an asparagus steamer on a electric hot plate (and also outside in a well ventalited area). You can cold polish with a rubber maid box with your parts elevated on a metal hot pad/ cooling sheet.
Create an index/keying feature in the original 3D printed part, this will help line up the A/B parts accurately, also the finished molds were faced using a vertical hand mill.