Our lane change cards are custom CNC machined from 1/8" black flexible expanded PVC. All cards have an integral 2-1/2" long tab along the bottom that fits in the slot on the track.

Each lane change card is custom made one at time. You can specify the color of the lettering, and color of the outline you want.
 

The picture is a sample of one made for Ron Hershman of Fast Ones. Thanks for looking and please check out my other slot car related items!