Here's a video ! It's a BEAST !!!!
I had some left over ABS and PETG plastic that I used to print my handle. I suggest PETG. It's the most durable. I used one momentary switch and one on-off toggle switch. I used two 18650 batteries in series and 3D printed these great battery cases to slip in the PVC tube:
The switches are wired to connect the negative wires. The toggle switch is a "Safety Switch" it's connected to the negative wire of the batteries and one post on the Push Button Momentary switch. Once the push button switch is engaged it connects the negative wire of the battery to the negative wire of the "spark" unit and BANG. The positive wires of the battery to the "spark" unit are permanently connected.
I glued the handle together with hot glue and used beads of glue to wedge the handle into the PVC tube. The batteries don't wear out when not using it. When they finally do need charging all you have to do is charge them. I haven't gotten to that point yet.
Great protection on trails where stray dogs may be encountered. Cheap and easy to make.