I designed this Lionel Fastrack O-gauge train trestle set in Tinkercad. I designed it to look similiar to the Lionel graduated trestle set you can buy. It is easy to print and does not require any supports. Each assembled trestle requires 3 pieces; Base, TrestleX, and Track holder. The TrestleX piece will press into the Base and stay without glue or screws. The Track holder screws onto the top of the Trestle with a cheap #4 panhead sheet metal screw (1/2" - 3/4" is good, but no longer than 1", Home Depot).

I redesigned the Track holder part for extra thickness on its curved edges (which holds onto the track) after I broke a few during testing. These are stronger and have not broken yet in testing. Print this part with 100% infill to make the curved edges solid. Use care when inserting (or sliding) onto the Fastrack so as to not over-stress the edges.

The Track holder part (as well as Trestle 11 and 11a) has a 3.5 degree slope built into it, so make sure it is oriented correctly on the track up slope and the track down slope. 3.5 degrees is a reasonable up slope for a train loaded with cars. Just space the trestles at 8" for that angle. A larger trestle spacing reduces the slope making it easier for the train to climb, but takes more track to get to the top.

20% infill is adequate for the Base and the Trestles.

I included two optional pieces (designated with an "a"), one is 6mm (0.25") tall and the other 133mm (5.25") tall. Each are optional in case you wish to add a bit of support at the start of the slope and/or at the top. Alternately, Trestle1a (5.25") can be used as the final trestle if 5.25" overpass height is desired rather than the 5.5" height from Trestle1. I think Trestle1a really is NOT necessary, but suggest using Trestle11a (0.25") to help support the start/end of the slope.

Update:
I added a level Fastrack holder without the 3.5 degree slope.It can be used for continuous flat elevated surfaces.

Update 7/31/2023:
I added "Trestle 11 w track holder 0 deg" by request. This is 0.5" tall with fastrack holder integrated into it. The has a 0 degree tilt so is meant for a level track. This can be used to help transition onto/between various carpets if needed.

I also added a file that shows detail in the height calculations. The first and last columns will tell you the trestle # and its total height. For example, trestle 11 will elevate the track 0.5".