Ideas on making an affordable and easy to build gradient.

Hard to beat the trestle sets for easy, and fast grade work.  If they are hidden anyway- why not do that??

One time-honored method: Trace around the track that will be elevated, then use a jigsaw to cut the plywood along the line (careful not to cut through your framing, though!) Leave it attached at the point where it meets the flat tabletop. Then you can bend the plywood 'tongue' into your desired gradient and jam pieces of wood under it to keep it elevated. (You'll want to glue or screw those in once you have them where you need them, of course.) Leaving the plywood attached at the bottom of the grade forces the gradient to begin slowly, which will help trains enter and exit gracefully, without the pilot striking the rail.

Personally, I use foam risers so i know what the % grade is an work into a grade gradually (...you can't go from flat to 4% instantly without having issues with couplers), which is probably not the most economical method.  BUT, i have seen people cut a narrow piece of plywood and bend it up on wood vertical supports to create a grade (much like a trestle set), so if your plywood is thin enough, you may consider that. Steaming the wood smay be required to make it pliable enough to bend like you want it.  I would think that's the least expensive option, though more time consuming.

The easiest way is to by the Woodland Scenics incline and riser sets.  The most affordable (and not too difficult) way is to simply cut your plywood with a jigsaw like NICKAIX suggested.

-Greg

Here is a video of my layout and me explaining what the track plan is like. If you have questions, just ask away. Also, due to the size of the video I had the trim it and turn it into multiple videos. Thanks. 

You don't have enough space for a 2% grade to get high enough to clear the section of track underneath.    You'll most likely need a 5 to 6% grade, which is fine.    How many feet and inches of track do you have from the start of the incline to where it clears the track?  I'm assuming you want a height of 6"  unless you are running husky stacks or flat cars with trailers.  The length of run will determine the percent of the grade (along with the assumed height of 6").

Regardless, it appears your plywood is already laid over homasote so I wouldn't suggest cutting through that for a grade - too much of a mess cutting through homasote.  I would use inclines and risers - store bought or homemade from foam.

I use Atlas track and have RRTrack software.  If you post the track sections from the start of the grade to the desired height and then the same going back down (unless you are using the same path to get both up and down via a return loop) I will duplicate in the software to get the grade and where and how high to place supports if you want to make your own.  I wouldn't get to it until Sunday as I have a several games to umpire tomorrow - it's how I pay for the hobby.

-Greg

I would do what NICKAIX suggested above for the first 2 feet of the incline, and obviously the last 2 feet at the other end.    In between I'd use plywood:  a 2% grade equates to 1 inch of rise every 4 feet.  (1/4 " per foot)....   I laminate 2 x  1/2 inch plywood together for my raised track sub-roadbed, why ....   Because  it's affordable, easier to cut with a jig saw and I stagger the joints so I end up with a pretty rigid 1 inch thick sub-roadbed that resists flexing and only requires supports about every 18 inches.    I use a 4 foot level and 1 x 1 inch block under one end of the level so I know I climbing at exactly 2 degrees over the length of the grade.   

Thank you for y'all's feelings and ideas after seeing what I have got. So far I think I am going to use the foam risers from woodland scenics to start the gradient and then transfer it to plywood and support posts. Thinking back I can see that there is a problem with the gradient on the last section of track that goes back down to the ground level of track that goes by the back wall. Like they say, just wing it.