Has anyone tried coating/infusing the surface of porose model material such as WSF? I'd like to improve the strength and chemical resistance of this and other materials.
Yes, epoxy is a good choice. It will reduce the flexibility though, and a thick coating can crack if bent too far. The big plus is that you can add fills like pigment or UV absorber. Definitely do not use polyester or vinylester resins, they are way too brittle.
So what type/brand of epoxy did you use when infusing? What was the outcome? Can you give more details?
I use Z-max brand which is a low-viscosity, long working time epoxy designed for infusing 3D prints. You can buy an equivalent product from companies like West Marine. It is made for repairing and coating boats. You can buy special hardeners that are water-clear or have a very long working time, which is important when you are trying to get the most out of a batch of expensive epoxy and coat as many things as possible. You may want to go with a clear-coat epoxy which, while maybe not as flexible, will have a nice gloss finish and come with the UV inhibitor. Some other epoxies will "blush" and have a cloudy look unless you polish it. I just saw some 1 1/2 pint kits here for $40 + shipping.