Looks like a fun job. Did each cube get engraved on the machine? If so, how long did it take and how much melting took place?
If I had dozens of these to do, I think I’d use the CNC to make a tool that could “brand” each cube.
I bet the branding would not leave the white contrast only clear and hard to see. Maybe fill with fruit juice or colored water and refreez for contrast
Cool use for the machine
Pun intended
I’m currently rebuilding the MPCNC for aluminum milling with the intent to (among other things) make brands that could be used to melt into the ice. The Bumble LR build can make a conservative 16 cube engravings (each router) so 32 at a time. If I were more efficient I could get 40 but 32 is good enough for me and leaves plenty of excess for me to dial in the saw that cuts each cube out.
A simple run takes about 4-6 minutes and there is no melt at all EXCEPT the snow that hits the router, melts and then drips back to the ice. I’m working on a solution for that but that’s way down on the priority list. I’m only ever going 6mm in and have a 6mm DOC in the CAM.
You are correct. Engraved cubes without the snow fill do work but it’s much more subtle.
How high does it need to be covered? Kind of extend the base plate or attach a plastic bag open at the top for heat but restitution at the bit?
I’ll get some good pictures next time I have it running - you’ll see where the snow hits and melts and then drips. We’ve got cooler mornings coming in a week or three so I expect to be running it a lot. Also the LR32 - THAT’S the one I really wanna get going - haven’t tested it yet.
My thought was to build a sort of inverted fencing cup (imagine the sword hilt cup that covers a fencer’s hand) that would screw to the vac hose mounting screws. The primary aim is to direct the wind from the routers away from the ice surface as earlier this year that was a bigger cause of melting than the dripping. if I could minimize the drip at the same time that’s a bonus.
Use a air blast to direct the drips coming from a known position 
to a safe direction just to a safe drain