Cutting the pipe channel


I started out trying to sand the cavity with the 3d printed mandrel and 80 grit paper but quickly looked for a faster way. I formed a copper wire around the mandrel


I sized the wire around the outer pipe


Turns out it was about 2.25" in diameter


I formed the wire to fit in the hot wire cutter and it immediately fried the cutter.


I then mounted it to my soldering gun and it got hot enough to cut the foam... but slowly


I rigged a quick depth of cut guide


Then cut the channel freehand following lines drawn on the foam


It wasn't perfect but was good enough


I used the mandrel to clean up the channel


First test fit was good


The pipe exit hole was pretty bad and would have to be cleaned up