Nice work. Non-revenue equipment is always fun to build, especially if you're freelancing. I built a water car from an old Tyco 0-6-0 tender. Cut out the cast coal load and built a bunker, complete with removeable coal boards, added some grabs and ladders where appropriate, and fitted a coupler on the front end. I painted it boxcar red, as I recall seeing a similar one on the CNR about 35 years ago. It looks good in a work train or just parked on a siding near the shops.
Wayne