Having done the fitted version, I've also turned out a trio of the unfitted 21 ton mineral wagon.

This is a Chiver's MDV modified to remove the top doors (with a very sharp scalpel), and mounted on a Parkside chassis to represent the unfitted welded variety which nobody does a kit for. Even in 4mm scale there are plenty of common wagons that aren't available as kits.

It's riveted cousin is a straightforward build of the Parkside kit. The only modifications are buffers, wire handrails, a decent tiebar from 1mm nickel silver strip, and some spare door spring from the Chiver's kit

Lastly, a Hornby ex-Airfix riveted ex-PO mineral - a very nice body moulding like most of these Airfix wagons. A query on here pointed me in the direction of a photo of a suitable prototype. This has the same Parkside 12' chassis as the other two, but with MJT W irons and springs, and 51L heavy duty axleboxes.

Next step is to paint them all in a rusty c1970 grey! The weird pretend MDV livery on the Hornby body has to go