Combat Patrol Leftovers

After building the combat patrol set, I have many leftover pieces (mostly from the plague marine squad). Are there any straight forward uses for all of these pieces?

I’m new to all things miniature building and painting. I know there are lots of options out there for printing, sculpting, etc. for custom pieces. However, I‘m curious to know if anyone has advice on an easier to go route, such as a base body set they know of or another set of models that pieces can be used for.