This design builds on my knowledge of Bauhaus architecture of Tel Aviv, together with a love of Playmobi

Design Process

Research:
Perhaps the best Playmobil set I own is the early castle.
Within this you can see the wonder of the creative mind: https://www.firstversions.com/2015/10/playmobil.html

When in Tel Aviv, this is a great resource for Bauhaus architecture an information
http://www.bauhaus-center.com

Conceptual idea:
Here are a few of the designs that I have made in 2018.
https://www.thingiverse.com/thing:2830262

Progress:
I have printed the wall out and it fits into previous Playmobil castle. See below

Therefore the modifications on the wall pieces can go ahead

The joins I haven't tested that they fit together.