VHM-306
thingiverse
People use a box for VHM-306. The audio jack is 5.5 x 2.1 mm DC. You can find similar jacks at https://www.ebay.com/itm/10pcs-5-5x2-1mm-DC-Male-Jack-Plug-Adapter-Connector-DIY-Components-ca-/312481098151?hash=item48c15329a7.
Download Model from thingiverse
With this file you will be able to print VHM-306 with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on VHM-306.