Raising the gantry to increase the clearance under spindle
(Working in progress, more to come ...)
Currently, for both Zen CNC 7x7 and 12x12 model, the clearance under spindle is about 2 inches. It will serve you well if you are mostly cutting on flat or not that thick pieces. But if in case you need to put a thick block under Z, you will face the problem that there is not enough clearance under the cutter, or the machine frames are in the way to obstruct the necessary movement. If that happens, you can easily raise the entire gantry to increase the clearance. It is a DIY kit, and you are free to change or modify anything to the machine.
There are many ways of doing this. Here I will just show you the way I am doing it and hopefully it will give your some hints. You can use any material such as plywood, plastic or even metal plate. But I have plenty of PVC scraps laying around, so it is my choice to use.