No other way?

Concerned Water

Do you have to make a Juniper OS for GNS3 or are there OS's already made available for download?

f0rgiv3n

If you're willing to spend some $$ there's a thing called Junosphere. It's a hosted solution where they have a virtual lab environment for you to play with.
Junosphere Virtual Junos Routers and Networks - Network Virtualization Software - Juniper Networks
It says on there, $50 gives you a 24 hour access. I believe this is 24 hours of you logged in using them. Seems reasonable to me.

NetworkVeteran

I believe this is 24 hours of you logged in using them. Seems reasonable to me.

It's a great deal. For $50 you get ten 24-hour blocks. Once a block is started, it runs to completion. E.g., you may only get 6-8 hours per block. Also note, that's one device. To run three devices for 24 hours costs three blocks. However, JunOS is capable of dividing one physical device into several virtual devices.. so two devices are enough for most basic scenarios.

I couldn't imagine spending hours to setup an Olive with such simple/cheap alternatives available.