Summary

Here are files for a fully planked BR High Goods Wagon. They are drawn full sized so scale to suit your model.

The BR diagram 1/034 was originally designed by Oliver Bulleid for the Southern Railway during WW2. This was SR diagram 1375 with Morton brake gear. More were built for the LNER (diagrams 178 and 210) and for the Ministry of Supply. After Nationalisation BR built more to the same design under 1/034.

Suitable buffers can be found elsewhere in my Thingiverse designs.