Script to push on multiple devices

Hi Thwack community, I'm new here so excuse me if I'm not following the right procedure.

I'm not a programmer and I need help for a script so I don't have to spend 2 weeks full time for doing a little change in my whole network.

I basically need to change every snmpv2 config in my network topology for snmpv3. The problem is that I have multiple models of switches;

-Cisco 2950

-Cisco 2960

-Cisco 3750

-Cisco Nexus 5000

-Cisco Nexus 7000

So I need a case with multiple "version contain XXXX" values and where I would be able to add the commands related to snmp in.

If it's another model then the ones that I've wrote, add the IP in a list that I'll be able to see later. If it's not possible, just skip this device.

Is there a way to do that?

Thanks a lot!

Metalshad