There have been many posts about people running truenas as a VM in proxmox. There are a few things to consider that I'm not well versed on, so I suggest doing some more in depth research, but it's definitely possible (I did it myself up until the end of last year).
One of the easiest ways to get the hard drives into truenas is to connect them to a raid card running in IT mode, which allows the OS to directly control the drives (do not raid them, truenas wants the raw disks), and then pass the raid card to the truenas VM
We're printing with Nylon at work. Great material but it vacuums up water and if it's absorbed any amount it prints like crap.