This part replaces the Alien armature on an Attack from Mars pinball machine. You need to attach this to a solenoid plunger. It's up to you to determine the proper plunger - personally I've used the same ones as the kicker in an AFM and they've worked well. This part just happens to be unavailable while the kicker armatures are available.
NOTE: This part does NOT COME TAPPED! The model file includes threads but they aren't printing properly. You must tap this with an 8-32 tap. It tapped well for me.
Version 1.1: Shapeways was declining the parts because near the top the wall was less than 7mm thick. 2 changes were made
1. Removed the threading since it doesn't print well anyways, changed the hole to a #29 diameter.
2. Added a little thickness to the screw hole just to get past the bracket mount, where the part was considered too thin.