I own a few boxes with construction material from Fischertechnik, made in Germany.
I think it can be combined with Littlebits as construction material to make interesting projects. They have plenty components to build dynamic and static things.
For product information you can take a look at their youtube channel.
They do have retailers in the US and Canada also:
Even more videos:
A really nice example of a Fishertechnik sorting machine, that could be controlled by Littlebits electronic: