For British H0, the Ratio kit for a GWR Iron Mink is like inverted Playcraft: the ends are about the right width, but the sides are much too high, and the end profile looks wrong. This is my first take on this kit to try to make a passable 'period' wagon.
I began by filling the holes for the buffers and drilling new ones at 20 mm centres.Then I cut the buffer beams off the ends, and started assembly by fixing both sides to the floor. Then I added the buffer beams, followed by the two ends trimmed at the bottom to match up with the sides. I really wanted to trim at least another millimetre from the sides, but I felt doing this would make the doors look too squat.
The buffers are 4 mm scale ones by ABS, and the wheels are 10.5 mm ones by Steam Era Models on the Ratio axles. The new wheels bring the buffers down to the proper height. I cut the brake gear part into two pieces and glued them in so the brake blocks are near the new wheels, and added a scrap of styrene strip to join the mechanism back together:
The original doors looked wrong as soon as I put the roof into place so I cut the tops off the doors, filled in the body sides here with styrene, and glued on new "flush" doors and rain strips. So the model might be a former gunpowder van. The model is now 32 mm wide across the rain strips, this is 1mm too wide for the loading gauge (0.5 mm each side) but the overall size looks reasonable against this true-to-scale ferry van from Modellbahn Union:
The model has a piece of sheet lead inside and weighs 37 grams. There is room under the floor to add some more weight if this is not enough. The couplers are Kadee "long shank, centre-set". These are long enough to reach beyond the buffer heads whilst keeping their draft gear boxes behind the buffer beams.
I don't know whether the underframe is supposed to be a 9 foot wheelbase in 00 or a 10 foot wheelbase in H0, but the mouldings are finer than those of a 1970s Lima wagon, and so I guess they are closer to H0 scale. I want to try this kit again one day, but I will choose a prototype before starting.