This is the Lomo DIY plastic slr. There is a clip of the camera being put together. Interestingly the builder spends nearly as much time putting the stickers on as putting it together. Ha!
I often disparage Lomography with its principle of taking deliberately bad pics (but thanks them for popularising film use - thank you Lomo) but this is a mere £29. That's not bad and cheap compared with some of their other stuff.
I haven't been able to find out how the mirror works - I doubt it has instant return but does it deploy automatically?