Here it is : https://github.com/Novatux/Mesecons_simulator
Commands : z and s to change the viewing level, r to change the plane.
The first button adds cells in the directions you want (if you find the grid too small)
The second only makes some stats about what materials you are using (if you want to build it without creative mode)
The third one allows you to toggle switches (and later to program microcontrollers)
The fourth is to rotate gates and insulated mesecons (anything that can be rotated).
The remaining buttons add or delete mesecons objects.
Use Ctrl-o and Ctrl-s to open/save a file.
Here is a screenshot (taken by Jeija) :
It requires Python, with Tkinter and Pickle.
