Whenever you work on a model there is substantial risk to scratching the paint or damage. I live my life by O’Toole’s Law…O’Toole thought Murphy was an optimist! The best rule it to reduce damage to the greatest extent possible. Some of this just easy, like using foam rubber – you can never have enough foam rubber. I don’t use slings when I model; I just position the model using various pieces of foam rubber placed to position the model properly. The second tool is masking tape. If you don’t want it scratched, put masking tape over it. It’s great for anything that sticks out, like cylinders, air pumps.
When I need to work on the side of a model I use a wood support with foam rubber wedges to hold it firmly on its side.
Last, is a boiler support. If you remove a boiler, don’t lay it down! Take a wood base drill a hole in the center and put an upright pipe, bolt, or large wood dowel securely in the hole. Put a bit of foam rubber around the base to protect the boiler front edge.
I hope these tips are helpful.