I've carried my laptop around in so many different bags over the years ... sling bags, tote bags, waterproof messenger backpacks, IKEA backpacks with laptop sleeve compartment, drawstring bags. I usually pick the bag depending on the occasion ...

bike ride in the rain? -> waterproof messenger backpack

downtown stroll to satisfy my inner hipster? -> tote bag etc ...

All I know is that I'm a "single compartment" person ... I've always found that having a separate compartment for everything just comes at excess weight and loss of flexibility.

I'd give the movie prop a try for sure. Still looking for a decent source of Tyvek to take an attempt at making my own bag (it's not super commonly used where I live).