Working on furniture or any construction activity that yields experience in the construction skill, including in building mode. Protean planks and flatpacks work. Limestone fireplaces are recommended as limestone bricks can be acquired for 21 gp each from the stonemason in Keldagrim and sawmill operator in Prifddinas. If your house is in Rimmington, there are also clay rocks close by for unlimited clay fireplaces without the need to bank.