Can we build a Three-state logic gate using only transistors (or basic logic gates)? If so- how is it built?

I'm trying to build a model for an 8-bit computer in LogiSim, and I'm trying to find out if it is possible to build everything using transistors, voltage sources and a clock. 

I know that a Multiplexer can be used instead, and that it can be implemented by logic gates, but I prefer to use Three-state logic gates.