Here's one of the handiest things I have created for the CR10 so far; a set of dovetail style quick-connect fixtures for the OEM hot end and the laser engraver. One can swap between printing and engraving/cutting in a matter of less than a minute. The reason I decided to go this route instead of mounting the laser with a magnet is that I wanted the least amount of offset from the normal tool center when going between printer and laser.
To use, simply turn the cam lock lever to the left to unlock the current tool, remove the tool, put the new tool on the carriage mount, and lock it down with the cam lock lever.
This mount set adds only about 8mm to the Y offset, which can be compensated via firmware adjustment, or via moving the Y limit switch forward.
I printed out an extra "Carriage Quick Mount" and attached this to the CR10 frame for storage of the unused tool.
Sorry, but I don't have the info on hand right now as to what length M3 screws you'll need for this mount. I'll do my best to measure these in the near future, but I simply used screws that I had in my "junk drawer". I can tell you that you'll need five M3x0.5 nuts.
I used ABS in a prototype, and printed the final in PETG only because I had run out of ABS. I prefer the finish and feel of the ABS print, as to me, PETG is too "flexy". Just prying it from the bed flexed the parts noticeably, whereas with ABS, the parts were rock solid.
I'll likely order some ABS and re-print this. The reason I didn't use PLA is because in my experience, even though there isn't anything extremely hot with a working hot-end cooling fan, PLA does tend to distort even under only moderately warm conditions, such as would be created by the heat coming from the heat sink. If you print this from PLA, please let us know in the comments section how well it holds up after several prints.
Note: The stock hot end mount is the only one that really needs support.