I am currently building a track entirely made out of cardboard , tape and hot glue . It's almost finished , so I decided to share my process of building a curved turn.
Here's what you will need to make it:
You obviously need cardboard too :
Start by drawing a semicircle on your cardboard, and then another bigger. 4 cm seems to be the width for 1 car, 8.5 cm for 2 cars.
To make a banked turn, draw a line like in the picture below. It will determine the amount of banking of your turn.
Then, cut the turn:
To allow for the cardboard to fold , cut the back of your turn halfway through like that:
It will then bend easily.
Cut a piece of cardboard, and tape it temporarily this way:
Then, cut an outline like in the pictures below, and tape it.
Here's your banking:
Cut some walls like these. The smaller ones will go in the inside lane while the bigger ones go to the outside lane.
Tape them in place. Don't be scared to use a bunch of tape.
To make the entry and exit of the turn, cut two pieces of cardboard like that. It should be 2 cm wider than the width of the road in the turn:
Turn the road pieces and cut them halfway:
You can then fold the sides to make for a side wall:
Use tape this way, the walls are less likely to move this way:
Now, we need to make the straight pieces match the inclination of the turn:
We will need to fold it on the line I drew on this piece:
Again, cut the piece halfway, and fold it:
All the pieces are ready, now tape them in place:
The turn can now be added to your track:I hope it helped.