Having admired these coaches for some time, I finally decided to buy a rake of these from Rob at Swift Sixteen. That's two of these, a Half Observation Coach and a Brake Coach plus all the fittings.
The two sides and ends were sanded on the inside with wet & dry, cleaned and assembled using Supaglue.
Although there are groves and tabs to assist with the assembly, I would recommend the use of a set-square.
As each piece is detailed to a very high standard there is very little need to remove any moulding debris.
The next stage will be the chassis.