So for future reference if anyone has a problem with the muzzles of these being too thin and Maim unsupportive telling you your printer is just not calibrated, you can cut the muzzle at 45° right after the eyebrows and make 3 to 5 copies of it that stand in the same place but each of them 1%, 2%, 3% etc smaller in that order. This will create a muzzle that is as thick as the rest of the base. No need to go into any CAD software to solidify or anything. Just adding a couple of smaller muzzles inside the main one.
Viewing post in Canine Fursuit Bases comments
You are really putting a lot of extra work into something that was probably an issue with your slicer or your filament. They're supposed to be thin, it reduces weight. You're going to make a VERY heavy headbase if you print it twice as thick.
but also
MeshMixer> Edit> Make Solid > accurate, accuracy/density 300-500, offset 0.8-1.6> plane cut to reflatten the bottom
would not recommend unless you're doing a foaming or spongy TPU print, and you will need to print the eyes smaller and nose/eyelids bigger (if you're good at math, you can math it, if you can't do math just print a few different sized versions at low quality to figure out the size)