This kit consists of a lot of different parts. This is the N-scale 135-foot turntable base (part #NT-135, and indexing kit part #LK-110). It is a hydrocal-casting mounted to an MDF base plate.
The motor drive unit parts (parts inside of the box are shown outside of it; part #MK-111)
Structure for the turntable controller.
The package comes with a collection of construction pages. I hole-punched them and put them in a binder. This particular photo shows the bridge tie template.