Firstly have a look at these; Swansea docks sidings over a long period. Lovely.
I guess most people would buy a seat. I needed a bench to stick at the side of the station building on Morton Stanley. Nothing too ostentatious, just a simple rural seat that would have been knocked up out of old bits of fencing or similar. 15 mins and some scrap 60thou 28mm long, 8mm high and hacked at with a craft knife. Two triangular fillets stop our tubby gent crushing the whole thing.