I have a momonari kabuto I am parting with. It was made by Brian Brown a while back (pics of it are on his armory site), and has sat unused on my shelf ever since (for a variety of reasons related to my mostly not fighting).
It is slat-back, full menpo, with pre-drilled holes to attach a shikoro and yodare kake. The menpo pivots up a bit and is held down by a strap and buckle going around the back (to be hidden under the shikoro, obviously).
It's 16ga steel case hardened after completion and before powder coating. Brian assured me it will hold up. I have not put that assurance to the test, so you'll have to talk with him for any issues.
It is also fairly large. I have a big 24"+ circumference noodle (7.7" diameter), so it has an interior circumference of 30" (9.6" diameter) to allow for 3/4"-1" of padding. No point in having your brains addled.
It is a really nice piece I paid $850 for new. It is still new. I am accepting offers. For an accepted offer, I'll take a PayPal gift (not big on their outrageous fees), Money Order, or Cashier's Check. If you are somewhere in the Western Montana or Northern Idaho area, we could probably just meet up to do the deed also. I find myself in Missoula, Kalispell, and Sandpoint all the time.
I'm not crazy desperate to part with it or anything; just going a completely different route with a new persona and suit of armor, and it would be a shame for this to never be used.
Pics (I hope):
