OK, I found and downloaded the export to SH3F plugin but I clearly don't know what I'm doing because, when I tested it, it exported pretty much everything I've ever imported into Sweet Home 3D, not just the objects I wanted.

So I've put all the models I've made into a .zip archive which should be able to be opened by any computer - Windows opens it by default these days and xarchiver works a treat for Linux, so I guess there should be something for Mac.

The perforated tubes in the picture are not my creation, they came from CGTrader - here -the invisible triangle opening in the wall is here, the invisible box opening is here and the chrome cylinder is here - I owe a lot to this forum and have learned a lot from Hans, Cecilia, Emmanuel and Enko!

The zip file containing the primitives I've made is here - I've added some I've created in the last few hours and I've also included my vape model in case you want the characters in your scenes to have a safer option than smoking [:p]

The invisible cylinder should be imported as door/window so that it punches holes in the walls like the invisible triangle and cube.

As my original pic used right angle triangles that were based on the invisible triangle (not my own work), I made a right angle triangle in Blender and included models for that.

Upper and lower Semi and quarter cylinders and RATriangles are primarily for beading or making angle brackets so they are oriented in such a way that adjusting the width will size them appropriately.

Since I'm using an older version of Sweet Home 3D, I can't rotate objects on the X and Y axes so I've made separate models for different orientations - each should import straight into SH3D with the correct orientation using Add Furniture.

Hope you enjoy the models and have as much fun "playing with blocks" as I do.