You asked about bolsters. Specifically the ones I use in the studio. Here is a link to the bolsters on Amazon.
I like these bolsters because they are firm, stand the test of time (and use), and are inexpensive. They also come in a variety of lovely colors. You can also remove and wash the cover.
If you think now’s the time for a new bolster feel free to explore one that meets your needs! If you don’t want to explore that much, and like mine, I’ve made it easy!!