Multiple keyboards etc

My last post mentioned keyboard layout arrangements at my desk. I have now completed building a double keyboard slide (two sliding shelves directly on top of each other) the purpose of which is easy access to two different keyboards/mice for working with two computers simultaneously. This job took all day on Wednesday to complete and since then there has been a bit of tweaking to get everything right. This has included fitting a locking pin to the top slide so that the depth can be adjusted and locked at positions other than all the way out, and shortening the runners on the bottom slide to reduce the depth when all the way out. Ultimately there was a bit of juggling to figure out the depth to set each slide to that is reasonably optimal while minimising depth to the most practical extent. The arrangement is that the right angle brackets have both sets of runners attached to the same brackets and both shelves are the same width. A lot of stiffening had to be added because the bottom shelf is relatively heavy, so extra brackets needed to be added and wooden rails had to be put on the sides. There are in fact four pairs of brackets supporting the rails.
The next step is to have two KVMs, one per keyboard/mouse set, to allow the keyboards to be assigned to any computer out of four. I am waiting for an order of USB cables I need to hook up the second KVM to be delivered. This is a much more versatile arrangement than having only one keyboard able to be switched.
The old keyboard slide that used to be on the right hand side and holding the Windows computer’s keyboard has been moved to the left side to be used for cups and any food items and has been adjusted to slope away from the desk so any liquid spills won’t go over the computer which is under the desk on that side. 
I am still experimenting with a shelf on top of the office drawer cabinet and have not reached a decision about having it or not. The replacement keyboard slide for the Windows keyboard to sit on is still to be assembled and mounted under the desk. At the moment I am considering whether I even need it there or whether to use some other arrangement as the dual keyboard arrangement will make it easy to use the second keyboard to control that computer. Alternatively a fully raised slide like the upper one will still allow me to use space under the desk for the 2nd KVM etc. Another option is to adapt the top of the desk to allow the keyboard to sit on the desk.

It looks like Borg is easy to set up on serverpc, I just have to install and configure SSH on serverpc to get it set up to be the backup host, it will have borg installed on it as well and uses SSH as the network protocol, more reliable and faster than a Samba connection.