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Casting a footed box?

I want to cast a small, footed jewelry box. about 2"x3", and an inch deep. I can cast the top separately, but the box must be hollow on the inside, and I can't figure out where to put the opening to fill the mold. I plan to cast the bottom part, then a piece to fit inside to retain hollow, but where should the opening be -- on the top edges or the feet? Maybe on the back where it won't show? How would I do this?

-Eddy


Paige Russell2 months ago

Hi Eddy,

Depending on the shape of the box (I'm assuming it has simple vertical sides) and the thickness of its walls, you should be able to get away with making a flexible silicone rubber cut one part mold – like I made for the rubber duck in Lesson 4. If the walls of the box are 1/4" or thicker, the following suggestion should work.

Follow the same instructions for duck, gluing the feet of your box model to the mold board.

When it comes time to remove the model from the cured mold, use an exacto knife to make a cut from the top left foot to the bottom right foot and then from the top right foot to the bottom left foot, making an 'X'. Peel the cut pieces back to pull out your box model.

Before casting the mold, attach some quality (aka sticky) double stick tape to a small flat piece of wood, plastic, or hardboard that fits just inside the feet openings without covering them and place it on the cut 'X'. Flip the mold upside down and bang it on the table a couple of times. Doing this ensure that the cut pieces won't get pulled downwards by gravity and distort the bottom of the box.

Smooth-On's Oomoo 25 would work well for this application.

If the walls are vertical, but thinner, I would recommend making a 3 part mold following the instructions from this great instructable:

https://www.instructables.com/id/Mini-Nuclear-Powe...

Good luck with your project!

-Paige