The Huawei Honor 7 may be a flagship device, but compared to some of the competition, it doesn't cost all that much. The same can kinda be said for Amazon's Kindle Fire HD. That makes each device an okay one to muck around with.
Before you start flashing ROMs, you need a decent custom recovery. The Team Win Recovery Project is more than decent. In many ways, this is the top option available right now.
TWRP support has landed for Amazon's 2015 Kindle Fire HD, which isn't a bad piece of hardware. And as you've probably figured out, support has also arrived for the Honor 7 as well. Those of you with the phone may enjoy it even more once you're running different software.
Of course, flashing things means you run the risk of breaking something. Despite how much money you saved, bricking one would still be a shame. Exercise caution.