Has anyone found a good way of sliding a plywood p...

Has anyone found a good way of sliding a plywood platform along the length of EMT? I'd like to build a track saw, which would require moving a sled along the length of EMT. This would be equivalent to a linear bearing (like the kind used in 3D printers), but I can't find linear bearings with this diameter. It doesn't have to be frictionless, but needs more stability and less friction than a simple hole drilled in birch plywood. Even some sort of rigid plastic sleeve that I could insert into plywood that would reduce friction and provide lateral stability.