My FD is going to participate in a combat challenge this summer and we need some tips and tricks on how to build some props to train on. Keep in mind we do kinda what to keep this cheap. I just need input or ideas.

Props that we need to make:

Vent- Some type of half roof so that we can cut a 4x4 hole with an axe.
Keiser Sled- You have to push a 3' beam with a 8lb sledge hammer and you have to push it 5'.
I do have the specs.
Confined Space- Need to make some obstacles to craw through.