The CNC 3018-Pro doesn’t absolutely need home switches, but (in principle) they let you install a workholding fixture at a known position, home the axes, pick a preset coordinate system for the fixture, and not have to touch off the axes before making parts.

Having used Makerbot-style endstop switch PCBs for the MPCNC, this was straightforward:

The X and Z axis switches simply press against the appropriate moving parts:

The little tab stuck on the tool clamp provides a bit of clearance around the upper part of the X axis assembly.

The Y axis switch needed a slightly tapered tab to extend the bearing holder:

It’s made from a random scrap of clear plastic, hand-filed to suit, and stuck on the bearing to trigger the switch in exactly the right spot.

You can find elaborate switch mounts on Thingiverse, but I’ve become a big fan of genuine 3M outdoor-rated foam tape for this sort of thing: aggressive stickiness, no deterioration, possible-but-not-easy removal.

The switches need +5 V power, so add a small hack to the CAMTool V3.3 control board to let the connectors plug right in:

The solid models borrow their central depression around the switch terminals from the MPCNC blocks:

The OpenSCAD source code as a GitHub Gist:

The dimension doodles: