NOTE: This is for the old version of the MPCNC. I have not yet built the new one, but Allted says it no longer needs alignment (see the comments tab for his thoughts).
Updated 12/8/2016: Added the outer rings for the upper and lower mounts. Before you could get these from Allted's mount, but he has changed them for the new 525 MPCNC so I've added my own models for people who need them on the legacy MPCNC
This is a remix of Allted's DW660 mount for the Mostly Printed CNC. I was compelled to make it when I faced a board and had "zebra stripes" across my surface because my DW660 wasn't perfectly perpendicular (facing with 1/2 or 3/4 requires fairly precise alignment; see before/after picture above). I didn't like adding shims since it was difficult to get accurate and consistent alignment, especially on tool changes.
I decided to add adjustment screws into the design. You use the lower adjustment screws to move the bit away from the Z-axis home, and the upper ones to move it towards the home. Do make sure to balance your pressure with loosening the clamp bolts to allow the freedom of movement, and watch out for cracking the plastic with excessive force. Use a right angle block to place against the bit edge (I recommend mounting a 1/2" or 3/4" facing bit to amplify the alignment angle). Even better is to shine a light behind the right angle so you can see the small gaps of light showing where you may be out of alignment.
While I was in there I added nut captures to make it easier to add/remove the DW660 (no longer need to hold the nut with a wrench, leaving one hand on the DW660 and one hand with the screw driver).
For my non-US friends, I've only tested this on my US conduit based MPCNC. My model is parametric (I remodeled this in Fusion 360) so I'm hopeful the international edition will fit just fine, but do let me know if you print it and have problems (or it works!). If you have already printed the original Allted DW660 outer rings, you can use them instead of mine (but I've added those files in case you still have the older MPCNC and need them, as Allted has removed those files).
There are six total files available, three for bottom support (inner ring for US and IE plus outer ring) and three for the upper support (same). No supports/rafts are needed for printing.
Also see Allted's "DW 660 Perpendicularity Tester" for checking and aligning your DW660 (http://www.thingiverse.com/thing:1525661). And for a better DW660 mount, check out my other design for using a shoudless mount on the DW660: http://www.thingiverse.com/thing:1936874.