Colored building set – Kay Bojesen

Kay Bojesen (1886–1958) a toy designer, produced his toys under the name “Boysen Toys” in the USA.

KB’s licenses for the Netherlands, Belgium and Indonesia was:
van de Marel – van den Hoven van Genderen in Voorschoten.

More about KB:


FB USA 17 april 2022:
“Kay Bojesen, friend of Maria Montessori, collaborated with the Montessori learning Program in the Netherlands in the 1950s. Most of the educational items he designed for them were sold to schools–not in stores for private purchase. This is why so few collectors today have any of these pieces, or even know about them–making them very rare.”

According “GP”, see pictures above: The 45a boxes came from a former teacher of a Montessori school.
The “MP” boxes seems to be a bigger variant, which was sold on 2ndhands website.


Although the system on both photo’s looks very simular, the floor is his left hand, seems to be softer material, while the wooden boxes only contains wooden floors. Also the windows are interesting and beside that, it looks like the columns are a bit longer, compared on both photo’s…

Price list

Funny enough box 45 or 45a is not mentioned in the price list.
Number 46, seems to be: “Gekleurde konstruktie-bouwkist – 299.60 Guilders”, which means “Colored construction building chest”. Could be very well, that bigger “MP” box on photo’s above.

Very simular construction set: Zet-Z-Op

In The Netherlands. also a very simular constuction set Zet-Z-Op was sold by the company OKWA, but uses plastic parts. Maybe a cheaper copy cat? We don’t know.

Some system characteristics

Here a short list of some system characteristics and how it’s retrofitted into the virtual LeoCAD library:

Part types:Original:Virtual:
27×27 [mm]
Single color piece
Wall panelWood
Single color piece
Pitch size138 [mm]138 [mm]
Wooden system

Library information of both systems

Here an overview of the parts library:

The single category, consists of these part types:

Part types:Number of parts:
Unique shapes Boysen Toys13


Left: Boysen Toys. Right: Zet-Z-op.