Allow access to network device from internal LAN and guest network

Question

I have a network device on our main internal LAN with static IP address; that device is connected to projector and allows users to show their screen wirelessly. I need to allow guest users to have access to that device as well; guest users are conencted to our secondary guest network which is completely separated from the main internal LAN. 
 What is the easiest way to allow guest users access that one device only from our internal network? Thank you, Mark

BAlfson · Accepted Answer

Like Scott says, Mark, you just need a firewall rule like 'Guest (Network) -> {necessary port(s)} -> {device} : Allow'. Typically, a DMZ is more for devices that are exposed to the Internet or in a larger organization where different subnets have different access rights in the DMZ. 
 
Cheers - Bob

m@rek · Answer

Guys, thanks for all your help. I guess I was over engineering this request and simple firewall rule took care of it. 
 
Here's what I have: 
rule#1 Guest (Network) -> {8 ports required by this device} -> {airmedia} : Allow 
rule#2 Guest (Network) -> {any} -> {corporate network} : Drop 
 
Thank again :-)