Building your own sauna is a huge undertaking. People who are skilled with their hands may disagree with that, but if you have moderate handyman skills it is a challenging job.
First you’ll need to plan the design of your sauna. You have to know what size you’ll need, you need to plan the shape of your sauna based on space and preference, and what kind of sauna heater you want.
Prefabricated sauna kits are the easiest version of a homemade sauna to build. You’ll buy a package that includes 4 or 5 panels that simply need to be attached.
You’ll have insulated wall and ceiling panels, benches, sauna heater - basically everything you'll need.
You won’t have as much design flexibility as building a sauna or designing a precut sauna kit, but a prefabricated sauna is the easiest way to set up your own home sauna.