How do you make a selfbow with reflex/deflex and still keep it from following the string? I assume you'll have to back it, but wasn't sure. And I definitely don't know how you get the reflex/deflex to start with. Any help would be appreciated. Thanks!
Backing would mean it's not a selfbow! ;)
You keep it from following the string the same way you keep any bow from following the string. Start with a net reflex (tips in front of the handle) and tiller carefully.
You can use heat or steam and a caul to get the profile - or take out any twists, humps, bumps, doglegs and rollercoasters. There are plenty of posts around here on that; just do a quick search.