I've got a few competing ideas for a character. They're going to be female and squarely from the IDW-verse with all of its' characteristic lore and suchlike. 
Only problem is, I want to make an OC rather than playing a canon character, and I can't find any suitable art for a robot mode. Is that an issue, or can I use a description for their robot mode?
(The vehicle mode is easy - I can just use a photo of the vehicle they turn into, of course).