English patchwork star

I'm making a mug mat using a patchwork star.
The Create and Craft group that I run will be starting this project at the beginning of September. I've never done a star before so have had to practise in order to have a sample to show them and also to be one step ahead of the women.
Shall I slip stitch in place or do running stitches? I think myself that running stitches will be easier for them but slip stitching will be more durable for washing. But who washes mug mats?
We will put wadding and a back on it and then quilt just away from the star. It will be done over two sessions.
I'm quite enjoying it.