I don’t do a lot of deal spotting on this site but this is too good to go unmentioned. Squirrel Daddy has their Lower Vise Blocks on sale for just $5.99. These are machined from a solid block of HDPE and can be inserted from the top or bottom depending on what part of your lower you need to work on.
I ordered one along with some of their other armorer’s tools and it shipped fast and free. I have wanted a lower vise block for years and I just couldn’t pass at this price.