Abstract: A toy construction set includes interconnectable building blocks. Fluid conduits are formed in the blocks. The blocks are interconnectable to communicate their fluid conduits. Resilient seals are carried by the blocks and form fluid tight connections between communicating conduits of interconnected blocks. Tubular conduit members are insertable into certain of the building block conduits, and the block-carried seals establish fluid tight communication therebetween. Flexible hoses are connectable with selected ones of the building blocks and conduit members. The blocks, the conduit members, and the hoses are interconnectable to form fluidic systems communicating such fluidic devices as pumps, motors, valves, nozzles and the like. A fluid reservoir and building base assembly is provided for use with the set when a fluid system is being constructed, and for storing the set components between periods of use.

Abstract: Components of a toy construction set carry undercut male connectors and have elongated grooves for receiving the male connectors to interconnect the components. The grooves have first and second portions. The first groove portions are configured to receive and retain a male connector which has been compressively inserted into such first portions by relatively moving the connector along any one of a plurality of possible insertion paths including a path extending transversely of the longitudinal direction of the associated groove. The second portions are configured to receive and retain a male connector which has been slided longitudinally of the associated groove into engagement with such second portions. In one embodiment, the first groove portions are undercut to a lesser degree than are the second portions. In another embodiment, the first groove portions are not undercut at all but rather are configured to interference fit with a male connector, while the second portions are undercut.