I made a roller blind using a kit from JoAnns online and some extra curtain fabric I had from making the curtains for our Airstream. The mechanism is a cord that lets you stop the roller in any position, not spring loaded like the one that is in the bathroom.
I rolled the fabric around the core so that it hangs over the outside of the roller rather than closer to the window. That way it looks more like a valance and less like a rolled up shade when it is open.
To keep it close to the wall, I installed two coat hooks upside down at the bottom. The bottom of the blind is fused around a metal curtain rod, so the ball ends of the curtain rod hold the blind in the hooks.
Here's a detail of the hook at the bottom. It takes two hands to lower the blind below the hook, push the blind close to the window and then raise it up again so that it catches in the hooks.