I've recently installed a 2850n on a network, the customer also wanted a separate SSID for guest access, so i set up an additional SSID on its own VLAN and its own network range, this works fine. Now the customer wants their guests connected to the guest SSID to be able to print to the printer on the other VLAN, now i know that the idea of a VLAN is to separate the networks but is there any way of making this work?

Thanks in advance for any help.

There's two ways to do this, one is arguably more complex, you'd enable inter-LAN routing between the guest network and the main network, then set up a firewall filter rule to allow the guest network IPs to access the printer IP, followed by a filter rule after that to block access between the guest network (source IP) and the main network (destination IP).

The easier way is to set up an additional LAN just for the printer (LAN3) then under inter-LAN routing, set LAN1 and LAN2 to access LAN3 without LAN1 and LAN2 having access to each other