I noticed that students in the ARC competition struggle with keeping the Igniter wire correctly centered in Aerotech Composite Rocket Motors. These are designed to fit in E-F Econojet, Economax, and Enerjet rocket motors. maybe some G motors.

Based on the QJet igniter plug and a manufacture forum talk by Gary Rosenfield of Aerotech/RCS. Students refer to these as the “Witch hat” plug. 

See photo for typical insertion in the protype photo 2 different igniters and a 1.7mm filament are shown alongside for scale with the early version of the plug. The final version has a hole in the “witch hat”. A bright color of PLA is better in case you drop one in the field!