I didn't like the holder for first player in the original Terraforming Mars Premium Inlay be Exaggerator. The Tile Holder by Birkbjo worked well for me and I noticed that the first player marker could fit inside as well.
The original inlay has two of these circular markers. I'm not sure what the second marker is supposed to be. My game only has one, so I wanted a version with space for just one marker. However, I made a version with space for two markers if you have them.
If you're interested in the rest of the insert from my photos:
The author remixed this model.