The boiler is a made from copper, silver soldered together, coal fired and the engine should hopefully work at 80psi. The boiler will need to be photographed to show the boiler inspector the internal soldered joints or be taken to be verified so you can proceed with the build. Once finished the boiler will have to be hydraulically tested at twice working pressure and if passed a second check has to be made in steam to ensure the safety valves lift at the correct pressure and any other leaks that may occur from fittings etc are not present. The inspection is carried out by a local model engineering society and this is needed as well as insurance to run the model in public areas. The hydraulic test has to be carried out in the future at normal working pressure.