Bayko – Plimpton Engineering Company Ltd

“The world’s first and finest plastic (building) construction toy.”

Invented by C.B. Plimpton and patented in 1933. Bayko is manufactured by Plimpton Engineering Company Ltd, between 1934-1958. Bayko is taken over by Meccano between 1959-1960s.

Many informative sources:

Active facebook group,
BaykoMan, Melright, MeccanoIndex-Bayko,
Bayko Collectors clubs, Brighton Toy Museum


The Bayko name and logo are the Registered Trade Mark and are the Copyright of Transport of Delight.


GB422645, application date: Nov. 1933:

GB613767, application date: July 1946:

With the 1946 patent, gable constructions are added.

Bayko series

Year:Series:Sets:Material walls:
1934-1936First production#1-5 &
Bakelite (Phenol Formaldehyde)
1935Ornamental additions
De-Luxe set
A, B C

Colour Change
De-Luxe set (recolored)
‘Special sets’
All sets

Bakelite (Urea Formaldehyde)
1939-1941‘New Series’#1-6 &
1945/1946Post-War ‘New Series’#0-3 &
1949-1959Post War Plimpton
The Peak Period
#3X & #4
(Styron 475)
1959-1960sMECCANO Takeover#0-3, #11-15Re-tooled.
Short version of: BaykoMan – Plimpton Era Summary

Bayko Sets

Image courtesy: BaykoMan

Box & Content: ‘Post War Plimpton’


For good quality manuals, go to: Meccano Index – Bayko
If you have more proper scanned manuals, I’m happy to share them too.


Colors produced, during the years:

Malcolm Hanson's excellent display
Image courtesy: BaykoMan – Malcolm Hanson’s display board

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:
BasesBakelite / PolyStyrene
Hole spacing: 3/8 [inch] / 9.525 [mm]
Single color pieces
Diameter: 75 [thou] / 1.905 [mm]
Single color pieces
WallsBakelite / PolyStyrene
¾ x ¾ x 3/8 [inch]
19.05 x 19.05 x 4.7625 [mm]
Single color pieces
Bay size3/8″ (9.525 mm)Scalled: 10 [mm]
LeoCAD settings:
Draw line every X studs
Snap XY5 [mm] 1/4 stud
Snap Z1 [mm] 1/20 stud
Rotations30/45/90 [deg]

Library information

Here an overview of the parts library:

LeoCAD numbering system

Yes, this library is called Vayko…

Some parts need to be added togther (Dormer roof, Double opening door, etc). So the specific parts could have different colors.

In total: 101 unique parts. Variations of gable & roof styles are not included.

Part numbering/identification

For playing virtual, it’s more handy to re-arrange parts. Re-using the number system concept from L’Edifice, enables a more logic way to build virtual.


Since Bayko using a lot of colors for the same parts, these Vayko library parts are created w/o any special color. This enables the modeler creating his own color pallete.

Corner parts…

In LeoCAD it’s possible to rotate parts, but when adding a next item on top, the next part will use the same orientation and ends up bellow the previous part. That’s why corner parts having a left and a right version:

Some Vayko parts, having left & right in LeoCAD.

Building in LeoCAD

LeoCAD building animation
Vayko city ~8050 bricks…

This is actually a nice toy to play with, both in real & virtual. I’m also surprised by the various building possibilities, also found on FB. There are still enthousiasts printing there own unique DIY parts! 🙂
For game play, it’s very simular to the French wooden Bâtiss.