Nice... I've been looking longingly at the awesome tripod I have under my spotter as a gun tripod, it's a high end pro video fluid head..but it is so awesome for my spotter..Hmmm. Might have to look further at that. I do need a good rest for my home range and my toy fund is darn near negative lately.
I'm going to get some rubber mulch myself it's cheap and I have a storage box to sacrifice. Rather than cardboard I'll use a layer of the scrap survival suit in the cutout target window. That should last longer and reduce impact noise. I like the design a lot, cheap and effective. Also corrals all the lead, when it weighs 100 Lbs. time for a new one.