Two halves lock together.

These cam type locks work fine to keep both halves together. The cost about $2.50 each and come in various finishes and metals. They do not provide much benefit to alignment, so for additional precision, one could add dowels for location or even tabs such is found in a leaf insert of a dining table. Since the house will be built on this base the precision and alignment of the joining walls can be custom fit during construction. I chose not to add any locating features but to build the slides with little clearance instead for the sake of cost and the lack of any precision woodworking tools. This entire base only required the use of a circular saw and a hand held electric drill.