As far as I can tell no-one does a model of these early coal waggons and there are no pictures because these wagons did not survive into preservation times.
This type was narrow bodied and high-sided with end doors.
They had inside bearings and no centre buffers. They probably carried between 1 and 3 tons and were built as Boston Lodge 1862-64 [ Boyd pp339 The Festiniog Railway Vol 2 : 1975 ] There was at the time heavy traffic for coal, lime , manures, and general merchandise moving from Portmadoc to the inland towns.
Early Up trains hade the loco on the front followed by "general" goods wagons and vans, then passenger carriages, and finally empty slate wagons.
You can see the coal wagons in this FR 1871 photograph of Little Wonder on an UP train at Tan-y-Bwlch [ but the station is not yet built. ] The third and 4th wagons are former dandy wagons converted to coal carrying, then a mineral wagon, followed by the coal wagons with very odd loads!
Wagon base was plywood, solebars and buffers 6mmx 4mm hardwood.
Slaters FR wheels and axleboxes
The axleboxes were pinned with 3/64 rivets.
One solebar was glued in and the other assembled and then fitted so the axleboxes could be squared up.
Limewood planking was glued to a 3/32 ply carrier
Chassis and one side
Body assembled and glued to chassis.
One end [ doors ] has vertical planking. The other end horizontal.
I have not discovered why these wagons had end opening doors.
Coupling hooks attached
One coat of grey primer and one coat of red oxide. Black for solebars.
Black plastikard was used for the strapping detail.
Rivet detail
Coat of matt varnish and rivets painted black.
Now to put in some coal!!