This post contains all the 3D models to make an automatic spray coater using a manual spray pen and a 3D printer gantry system. The whole conversion process is detailed on Instructables :
https://www.instructables.com/Converting-a-3D-Printer-Into-an-Automatic-Spray-Co/
You can see a demonstration of the setup on YouTube:
https://youtu.be/Ixd39U7TLSI
https://youtu.be/er7cRqY1UCs
And the Arduino and Python codes for control and Gcode generation are on Github (see the wiki for detailed explanations):
https://github.com/RemiRafael/Spray-coating-Gcode-generation