In Wi 396 there’s a fine article from Andrew Pearsall that digs into how to build a Blast Shelter for your WW2 games and beyond.
If you want to have a go at the build yourself you might find it useful to have some templates – well, here they are! Get them downloaded and printed, then build yourself a fine new bit of scenery! Enjoy!
https://www.wargamesillustrated.net/wp-content/uploads/2020/11/Templates-Blast.pdf
