Update: After I moved on from my bread machine roaster I no longer had a use for this cooler and it went into the scrap pile. It worked really well though!
My bean cooler uses a squirrel cage fan mounted to the underside of a wooden box. After the roast I dump the beans into a wire mesh colander which is then put into the hole in the top of the box. Fan goes on, and the cooling commences.
Here’s a video of the thing in action: