This is a Start Line for a single lane to be used with a 2021 hotwheels track, see photo below. Some of the other starting gates seem complex, this is an attempt to simplify the concept and minimize the quantity of material used in 3D printing.

Assembly will require 1 hinger from a "medium" sized clothes pin. I've seen them at the dollar stores and hobby stores alike. The wood part of the clothespin is 48 mm (1.9 inch) long. Larger clothes pins' springs are too strong.