This is an answer to a question posted in the forum Here: https://www.thingiverse.com/groups/engineering/forums/general/topic:22405 "Inexpensive 3D Printed Stackable blocks to build a Playhouse. Taking the LEGO type block and scaling up is to costly in material and time to print. Is there a better way?" Since this design is a open ended box material and time is reduced by a lot You can fill these with expanding foam to make them even stronger.

I'm not done with variations yet but it gets to the point There is 20cm x 10cm x 10cm Block, Base and Cap There is 10cm x 10cm x 10cm Block, Base and Cap There is 20cm x 10cm x 10cm 90deg Arc Block, Base and Cap

I'm uploading a 45deg pitch block then I'll get to Windows, Doors and Flats.