here is a program, called "coaster" similar to UC3D minus tthe set pieces, screen saver, and coloring options, but you can landscape and make new pieces, and ride your creation.
high ;learning curve, unlimited options...
mforce2 goes somewhere in the 5000 ft. tall range... (No, really, that many zeroes!)
http://members.aol.com/lurker27/coaster.zip