I started with this one:
Which is very nicely designed but I needed some improvements. Firstly I wanted to have hotend closer to X carriage to extend my Y axis range. Secondly I saw some issues from part being cooled only from one side and different shapes of fan duct did not help so I designed double blower version.
I tried also to add capatitive proximity sensor but in the end I decided to stick with manual bed leveling as it is for me no problem.
For assembly I use M3 screws and nuts. Only for clamping you need two squared nuts. In pocked for squared nuts is hole so you can use screwdriver or some other thin tool to get squared nut to right position to be able to screw it together.
I added also X carriage. I found X carriage which was very similar to this but adjusting this STL file was too difficult so I decided to draw it from scratch and exactly according to my needs.