If you have the resources, consider to use the hot vapor method. It's faster than the other options and I feel the results are more consistently good. All this is done outside as the vapors are dangerous to one's health and also explosive. I used a large glass cookie jar in a double-boiler configuration. In my case, it is a hot plate with a frying pan filled with water. The acetone occupies only a few millimeters of the closed glass jar. One can view the internal condensation of the evaporated acetone on the glass. Once the level reaches the height to manage the object being smoothed, it is lowered into the vapor for twenty to thirty seconds. It is necessary to construct a secure object caddy. A piece of wire mesh such as hardware cloth will work, along with a wire cage to keep one's hands clear of the vapors. Any contact of the item with the caddy will leave a mark, which means one should aim for small contact points in unobtrusive locations. One of my better results can be found on Thingiverse, in the shape of a banana.