Password Protect SD Card Between Printer and Computer  

Simple answer is no.  An sd card is not designed with security in mind.  As with almost all hardware, once you have physical access you can pretty much do whatever you want with it, there's almost no security that can stop a determined hacker.  
While you can encrypt the data stored on physical media you need a pretty powerful processor to de-crypt  data on the fly. 

I am afraid from a practical standpoint that you need to control physical access to the location if you are worried about security, something you should be doing anyway.

You could always run octoprint on a raspberry pi servers and then you can take advantage of such powerful processors and the gcode wont actually be stored on the printer any more.

RE: Password Protect SD Card Between Printer and Computer

Makes sense, Thank you.

Starting to get help running printers and it will be harder to control access for me. Hope the farm software isn't too far off! 😅

Hope the farm software isn't too far off! 😅

Every time I configure a new instance of Octoprint I have exactly the same thought...

How many printers can an octoprint run?

I've been putting off connecting printer #2 to the octoprint network - do I need an RPI per printer or can one octoprint run more than one printer?

I don't believe Octopi officially supports more than one printer per Pi but I know folks have done it. Each of my printers has a separate Pi controlling it. Adds some minor costs--plus the nuisance of having to find a spare outlet in my UPSs-- but I don't want an overloaded Pi to croak in the middle of a print job. 

No reason why Pi4 won't do several printers if you really HAVE to or your budget is that restricted. Theres a YouTube that walks you through it, but really is it worth the risk?

Single OctoPrint instance versus several

Posted by: @dan-rogers

I've been putting off connecting printer #2 to the octoprint network - do I need an RPI per printer or can one octoprint run more than one printer?

I believe -- perhaps incorrectly based on older information -- that a single instance of OctoPrint only supports a single printer, but you can create multiple OctoPrint instances on a single computer (Raspberry Pi in this case).

I'd only caution that it is often nice to be able to work on printer setups independently, including occasional rebooting. I personally find one RPi per 3D printer works best. YMMV.