The bottom panel is hdpe currently and "trayed", but you wouldn't run this machine with flood coolant anyway. mql might work but the idea was to cut dry, suck away chips and rely on coated end mills.
I've seen people experiment with diesel heater pumps for mql, might try that some time.
coolant always ends up very messy. even mql lubricated chips can be a relative mess compared to dry cutting.
> but the idea was to cut dry, suck away chips and rely on coated end mills.
You can go through a lot of end mills cutting dry. This is less of an issue for hobbyists who aren't turning large volumes of metal into chips and aren't using high-powered milling machines. The main limit on milling speed is getting rid of the heat. If you're willing to run slow, dry cutting works. Or if you only cut materials softer than steel.
At some point, you get Machinery's Handbook.[1] For most of a century, machinists' toolboxes had a built-in space for a copy of that book. Now it's available as an app.
I like to think of wood CNC as a step in the kit to something better. If you do your operations rights errors can cancel each other out and so you get better results by having a few extra steps. Make the wood CNC, then use that to cut the molds to make a epoxy-granite frame, then transfer the electronics to the new frame.
I've seen people experiment with diesel heater pumps for mql, might try that some time.
coolant always ends up very messy. even mql lubricated chips can be a relative mess compared to dry cutting.