Graduated fastrack trestle o scale

The rise is about 1/2" per support which, over a 12 up - 12 down graduation, is about a 6" total rise.

If you can place a support at a track joint every 10" of FT, that would be great. However, most layouts use smaller track pieces which makes that impossible, so it becomes a compromise of trying to evenly space out the supports and trying to place them at joints if you can.

One tip when assembling FT is to use medium sized binder clips underneath to hold sections together and this helps, also.

If you're planning on buying a set, I would recommend the MTH set as it's sturdier and easier to assemble. Their set of 24 trestles has a 6.5" rise which works out to a 4.7% grade which is easily doable for most modern engines. In addition, the MTH crosspieces sit on a "floating" ball which means they adjust to the angle of the track, while most homemade supports do not.

Old layout I used wood supports for the track.

Something like an I-beam