Sorry for the double post, but I didn't see any edit function.
About making your own, it depends on if you need a gui or not. If all you need is a shell, one way to do it is to just create a trojan that sets up an ssh server on the remote machine. If you need user login info first, just incorporate that into your trojan. A gui would complicate things, but if you do some research about X/display forwarding and ask/search for the right questions on programming forums, you'll have all the information you need.