Is there any way, how to make dualboot on android device? I would like to have dualboot on my phone, because of making custom ROM. Is possible to have stable system on default memory and my custom ROM in development on my SD card? And if yes, how to make it please?

Many thanks :)
There was a few apps in early android day's, but it takes too much memory..

You're better off just using a nan droid backup and restore between systems !

If you just swap system and boot, it'll be quicker and you can work on as many ROMs as you want !

I used to run CM9 CM11 and CM12 when i was still working out CM 12