I have added an addition to the Wall Mounted Gastly evolution line folder - Mega Gengar! There is the version with the mounting holes and without as well as a version with the arms split from the body so you can make it a little bigger.
Supports for this one are very minimal if any, but you know your machines best so do what feels right.
You can find the files in the September folder and the Wall Mounted folder.
Have a good day!