Have built multiple ones. Cost about $150 (maybe more now with the cost of lumber going sky high) 4- 2X10X10, 2 sheets of thick plywood (the thicker the better), screws, and carpet (does not have to be green or indoor outdoor) Buy a large tarp and wrap it every time when done and it will last forever. I also have plans for a portable one that one person can carry. A little more complicated but you can take it to softball field and throw.