Woodworker and nice guy Alan Young wrote up how he modified an import Mill/Drill to add a depth stop. Might be interesting to some:

This caught my eye since I am in the middle of rebuilding an older Rong Fu RF30, replacing bearings, etc. Mine is the power down-feed version with the longer table which will be a nice addition to my metal lathe and HiTorque mini mill. - it's no Bridgeport but the thing is massive and sturdy compared to the mini mill. I'm pulling out the power down-feed drive and transmission to simplify things. My existing lathe and mill are handy for making a few replacement parts!

My friend Joe bought a couple of these and I've used his a few times - he gave me this one recently. I might add a TouchDRO that I've already built for the mini mill but have not yet installed.

One thing Joe did to his which helps a lot (without a DRO) is make a simple bracket and mount a 2" dial indicator on the front with a magnet. This gives him very precise Z indication which is more reliable and easier to read than the vertical indicator dial.