Theres already a trail building thread thats more popular so this one just kinda got sidelined a bit.
Eh, do dual slalom dirt jumps count? Building a dual slalom course using a jump line that was last touched about 5 years ago, quite a lot of work but should be insane fun once its done.
Heres the first big jump, I was using my dh bike since thats really my only bike at the moment