I hate how anything made is diy
Tarps can be made into many types of shelters. While the standard blue tarp is a good tool there are quite a few more compact camping tarps out there that are made out of tent type materials.
Cheap DIY Root Cellar or Emergency Shelter; spray insulation inside each layer of cement blocks for improved thermal regulation.
DIY Survival Shelters You Need To Know To Survive Anything | https://survivallife.com/survival-shelters/
Atlas Survival Shelters-Underground Bomb Shelters For Sale
There are a lot of ways to go about creating a hidden underground shelter. Here are 6 examples some examples of hidden underground shelters so you can get ideas for your own secure survival shelter.