Hint A1 - K'NEX Rods and Connectors
K'NEX is a hugely successful Rod and Connector construction system.
A major part of its success is that many thousands of different models can be built with only a very limited number of different rods and connectors.
The first photo shows the six standard lengths of classic K'NEX rod: 16mm, 32mm, 54mm, 86mm, 120mm and 190mm...
...and the second photo shows the eight standard classic K'NEX connectors: 8-way, 7-way 3D, 5-way, 4-way, 4-way 3D, 3-way, 2-way and 2-way straight.
In addition to "classic" K'NEX, the smaller-scale Micro K'NEX is available.
The third photo shows the seven standard Micro K'NEX rod lengths: 14mm, 25mm, 40mm, 63mm, 94mm, 138mm and 200mm...
...and the eight standard Micro K'NEX connector types: 8-way, 7-way 3D, 5-way, 4-way, 4-way 3D, 3-way, 2-way and 2-way straight.