Monoprice Select Mini ABS and PLA air duct

-=UPDATE=-
I have moved on to other projects so I have updated the last version I created as well as the .123d design file to make it easier to modify for whoever wants to.
There are still a few issues such as the PLA vent being about 1cm too long, and the tolerances are a bit tight.
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An air duct for the Monoprice Mini that clips on and has two bottom plates that slide into place. One is a block off plate for use with ABS and the other is a vent duct for use with PLA.
This is curre