I was tired of having the ships slide around so much on the dining room table so spent a few days looking how other people made their DIY starfield battle maps. Lots of things came up on the internet ranging from felt cloth (decided against this as it would just slide off the table) to yoga mats (lots of pros but relatively expensive compared to other DIY solutions). So armed with this knowledge of what others had done, I spent an afternoon (while doing other errands) looking for some materials and pricing them out. I ended up picking up two black anti-slip shelf liners (something like this but 18" wide and shorter) from the dollar store for $6 and taping them together underneath to make a 36" wide field. The mat looked good, gripped the dining room table well and the ships didn't slide so much when placed on the mat.
To make the mat even better, Penny and I looked up various star fields on the internet as references and spent an evening painting the mat. She had a lot of fun flicking the toothbrush of white paint on to the mat and adding some large pink gas clouds/planets/stars to one of the quarters. The following was our end result
We were happy with it, but I might try and find a way to make her pink celestial bodies blend better with the rest of the star field at some point in the future.