I cut down the box I was using to fit the depth of the mold rubber, covered it up with a posterboard blank cut to fit, and taped up the edges to keep it together.
The tape is important, as it helps to compress the rubber just enough to make a good seal between the two halves of the mold, but not enough to distort the shape of the mold itself.
I taped around all four sides of the box, including the "top", where the pouring and venting holes are.
I cut openings so that I could access the pouring/venting channels, but still get compression around all sides.
The resin's about $36 for 4 pounds, and I probably won't need more than 1-2 pounds of resin.
And now, we wait... for my resin to arrive, probably by next weekend.
