H1+ 18650 battery with Heltec v4 / v3 compatibility

This is the H1+ case modified to fit common 18650 batteries and with added compatibility with the newer Heltec V4 module. Similar to my previous model. Made with the request of and help from: @JLO_2137313 Also added separately printable letters model to print in a different color and glue in place for aesthetics, courtesy of: @JLO_2137313 Again: WARNING: LITHIUM BATTERIES ARE DANGEROUS. BE CAREFUL! I AM NOT RESPONSIBLE FOR ANY KIND OF DAMAGE!!! You can salvage electrodes from other battery holders and heat set them in place or you can just use folded up aluminum foil. A spring is heavily recommended.