If for even a split second you think you might benefit from having pre-made plans for a cold plunge, you need to buy these plans. Joe has thought through everything for you - and he's done this enough times to have tips/tricks that will save time. If you can use a miter saw, drill, circular saw, and a jigsaw - then you have all the skills required to do this. Everything else you'll see how to do in his videos. This project took me about 4.5 days working 6 hours per day.
I ran out of the maritime foam and had to use fence post foam for the final insulation (just for the last 6'' or so. It seemed to work fine. Having a furniture dolly to throw this thing on toward the end was helpful. Make sure you triple check what wood you're getting. Even with Joe's hyperlinked shopping list, I ended up at home depot more times than I planned. Go ahead and just buy Joe's kit with the pump, ozone injector, and LED - it's worth it and you're not going to save that much finding that stuff on your own. I also opted to get his cover because I think it looks better.
I painted mine with outdoor paint and sealed it with poly. Using a rocita 1/3 HP chiller (I live in Colorado).