Creating the bend requires heat. Lots of it. You've got to get acrylic up to about 200-250F in order for it to bend. I used a borrowed heat gun, the kind they use to remove old paint.
Here's a link to show you what it looks like:
http://www.toolbarn.com/product/milwaukee/8977-20/
Most tool rental places will let you have one for the day for around 10-20 bucks......
After you cut it to fit, but before you glue the rocks in place, put it on a flat wooden surface (not metal, it will absorb the heat) with the ramp section hanging over the edge. Then heat the area you want to bend ONLY. Keep the gun moving, don't hold it in one spot or you may distort it. Once you think its hot enough hold the flat part firmly against the surface and press down on the ramp. (Wear gloves). Use slow, steady pressure for about a minute or so, then release and check your bend. Keep doing this until the bend is where you want it. Remember, heat it just enough so it will bend, but not so much that it will distort or start to melt.......I haven't measured the angle on my ramps, but it looks like it's around 20-25 degrees.
I used silicone to attach the rocks to the ramps. Clean them with denatured alcohol first. Don't worry about cleaning the rocks, just rinse them under tap water, and let them dry out completely.
First I ran a couple of beads of silicone, then spread it with a small putty knife (kind of like icing on a cake). Don't spread it too thick, or too thin. Also do a small section at a time! Although silicone takes 24 hours to cure, it starts to "set up" after about 10 minutes. Do an area about 3"x 3".
The rocks I used are just those tumbled stones available at most pet stores. Pick out the ones that are flat and smooth, don't use any that are jagged or have sharp edges:
As you press them in place try to avoid sliding them around or readjusting them, (there is going to be gaps, there is no avoiding it) and once you finish, leave it alone for at least 24 hours!
Here's a rear shot of the resting ramp showing how the large rocks were set in place. Set them up first and work your way out using smaller rocks as you go. Use the silicone only at the contact points on the large rocks. If things get messy, don't try to clean it, you'll only smear it. Wait till it's dry and trim with a razor. Also note the rounded corner. You'll have to do this to avoid having the ramp make contact with the seal inside your tank.
One more note. If you plan on using a canister filter, make sure to cut out a section for the hose to go through.
Good luck!