coreboxes and bushings

After having much difficulty using the other corebox that I previously made, I decided that it would be easier to just have 2 or 3 coreboxes for the sizes I really needed.

There is 3 sizes, 1/2 inch, 5/8 inch, and 3/4 inch. The holder_corebox, print two and you'll probably have to file on them very slightly till the coreboxes can be slid in and out while being still snug. Just slip those over each end and it'll hold the coreboxes together while ramming the sand in firmly.

There is also two sizes of bushings, I tend to design pulleys and such with a half inch bore on here, but hate to have multiple patterns for the same item that has different sized bores, so I the bushings fit over the half inch rod up against the pulleys or whatever you use and it'll leave a cavity for a core in that size instead of the half inch rod.