So as some of you may know, I have designed/created my own binders for a very long time, currently working on my sixth design, and I am quickly finding the need for a similar item, and would love to get some brainstorming going to help me out.

The father forbids me from binding, so I've got to make sure I look boobied, or well, questionable, around him and not so much elsewhere. As it is winter, this is no problem, just slip on the bulky jacket for the ride and take it off once he's driven away. But summer will be fast approaching, and with it, I have less and less excuse to wear jackets. I'm trying to think of a design, or really any sort of alternative, where I can easily go from boobied to flat without having to slip into a bathroom and change.

I'm thinking redesign the binder so it can act as a sports bra, then be tightened into a binder. Or I can find a way to alterate a light jacket, such as a windbreaker, so it forms breast shapes when zipped halfway, and flattens out when zipped fully. That's how my bulky jacket works, magic I know, I don't know how to make that work on lighter material.

Any suggestions would be great. I put this here since everyone on the spectrum has dealt with this sort of thing, and could use ideas, even if they'd have to reverse them.

Wonder if you could wear a sports bra over the binder (since it would lay flatter than a regular bra) and then when needed, fill with a couple of water balloons (although you'd have to watch for leakage) or boobs made of pantyhose filled with rice (I know an mtf who does that) and then remove them once it's safe to do so.  Although the question would be where to keep them in the meantime...

The velcro-sided binders I have aren't terribly easy to adjust... but if you could find/make/whatever one where the back pulls across to the front, instead of the front pulling across to the back, it'd be easy to reach under your shirt and adjust it; although not terribly discreet in public I guess.
Some kind of in-between binding might also suffice. Something that could pass as boobs, but is still flat enough to not look totally weird on a guy. A little easier to pull off if you have some decently well-defined arms and shoulders.

Whatever you figure out, I know I'd love to hear it. Good luck. 

I'm thinking something that tightens with a string, that you can just turn around, reach under your shirt, and pull tighter.  Corset-like, except designed to tighten over your chest instead of your waist.  OK, might have to slip into a room for a moment of privacy, but it would be faster than changing completely.

Or you could just tell dear 'ol dad to get over it (unless you're still financially dependent).

Jmaxley: I stay away from anything that looks or resembles a bra, because when you wear a thin or tight shirt, the seams show, and then if anyone asks, you've got a load of explaining to do. Besides, I'm very touchy with my friends, hugging, cuddling, etc, so it's pretty common that someone touches my chest or back and asks me what I'm wearing. If the binder isn't of a shape that could pass for a brace [my usual excuse], well, again, lots of explaining to do.

Cody: OOOOH. Back to front. That is a dang good idea.

Eryk: My current design has double corset lacings, definitely takes some time to adjust. If I leave it looser, it just looks a flat protrusion. Got to adjust the seams so it might be more boob-looking.