Exercises for riders that only have four jumps!
horse training exercises
Pallet jump, fill with brush - fake xmas tree branches?
crosses made of horseshoes | ... cross country jumps (pics) at the Horse Chat forum - Horse Forums
Cross Country Course - Washington State Horse Park
Fast, easy, recycled. homemade cross country jumps #5
Cross country jumps
This is a fun little jump to make with spools! That's really skinny so maybe it would work better with 2 spools?
Cross country More
Adjustable cross country jump