Yeah, that is a really creative and efficient looking setup you made for yourself there. Kudos!
So I guess you could say that what I said should be taken with a grain of salt. It's not necessary for it to be shaped any which way.. The idea is simple: you want to trap as much moisture as possible but to still let light in. If you use some creativity, like ANC did here, you will be able to come up with something for a low budget as well.
kaiserAxel: What are you referring to when you ask if they are dangerous to order online..? Are you referring to a danger in being caught or a danger in the spores being damaged? Either way though I'd have to say that the danger is pretty small. I've ordered a syringe once which arrived discreetly - marked as lab equipment - and spores were all viable. I've also received a spore print from a spore ring. There are free spore rings in many countries; these are organizations that basically give you the spores for your specius of choice and you pay usually about a dollar for the return shipping. This worked and the spores I received were also viable!

Some smartshops charge ridiculous prices for spores you can get for free...
You can keep your grow box outside, but I wouldn't recommend too much direct sunlight, and basically a maximum of around 12 hours of light a day. The most important thing with your grow box is keeping it humid. If you aren't seeing water droplets on the sides you need to mist it.
Oh, and obviously, you can't keep the box outside during incubation - they need total darkness for this part.