From Frank Buss on hackaday.io:

Vectrex cartridge

This is my first version of a PCB for building a Vectrex cartridge. I used this for my Kickstarter project for the Bloxorz game. The PCB was manufactured by @oshpark , you can order your board here.

It fits in this 3D printed case from Thingiverse (you can order it here in my Shapeways shop), or in one of the nice new injection molded cartridge shells from Sean Kelly

Frank has launched a Kickstarter campaign:

Bloxorz for Vectrex, PC, Mac, iOS and Android

A puzzle game for the Vectrex, including a version with Vectrex graphics for PC, Mac, iOS and Android

FrankBuss has shared the board on OSH Park:

vectrex.brd