Hey Smithy thanks for the reply,
Yeah I just started using vase mode. Before I would just set the infill to 0% and have two lines, space between them and then joined at the top to form the wall. (So if the wall of a model was 5mm, I would have two walls, 0.8mm each and a 3.4mm gap)
There is no way to just have one wall and choose its thickness without changing the nozzle?