Keebio Iris v7 Case: m2 direct-thread sandwich

Remix of skrat19's Keebio Iris v4 case at https://www.printables.com/model/66218-iris-keyboard-sandwich-case 

Changes made in this remix:

• Updated hole patterning to fit Iris PE middle layers
• Tightened hole sizes to allow threading into the print rather than using m2 standoffs
• Increased size of top and bottom layer outer boundaries to closely match Iris PE middle layer boundaries

The provided files are modeled for the left side of the Iris. To make the right side parts, mirror these files in your slicer. Middle layers (with and without ergodox tenting holes) are provided with the tighter through-holes so the middle layer can be threaded into, but the top and bottom plate files should work with any of the existing Iris PE middle layer files at https://github.com/keebio/iris-case/tree/master/phoenix-edition-PE

Note that these are intended for use with the Iris PE parts, which cover Iris revisions 5-7 at the time of this writing. I tested this on an Iris rev.7 as pictured. The pictured test fit retains both the previous holes from skrat19's rev4 case and my new holes from rev7, for alignment measuring. The pictured test was also made prior to expanding the outer boundaries to fit the official middle layer file to provide measurement references when expanding the outer boundaries. adjustments to both hole spacing and outer boundary sizing were made with both this test and the official design files imported to fusion360.

NOTE on fasteners:

The through-holes are sized to allow m2 0.4 hardware to thread directly into the plastic, rather than using the m2 standoffs provided by Keebio in their plate kits. The top plate is 3.5mm thick, the middle layer is 11mm thick, and the bottom plate extends past the middle layer by 1.5mm (an additional section of 1.5mm thickness extends into the case, offset from the middle layer boundaries by 0.5mm). This means you have a total screw length clearance from top-to-bottom of 16mm. You can use any combination of m2 hardware not exceeding this total length. This allows compatibility with most m2 hardware lengths and quantities available in amazon hardware kits and provides flexible combinations of screws to circumvent a mismatch between available quanitity of a given screw length and the amount required for full assembly of the case.

examples of screw combos:

• m2x16mm screws going all the way from the top plate, through the middle layer, and into the bottom plate (20 x m2x16mm)
• m2x10mm screws joining the top plate to the middle layer, and m2x6mm screws joining the bottom plate to the middle layer, or vice-versa (20 x m2x10mm, 20 x m2x6mm)
• m2x8mm screws for all holes, etc. (40 x m2x8mm)