Thanks. For the picture slot, I just recycled and cut a piece from an old clear plastic envelope. It works well enough for personal projects like mine. Something like these: https://www.amazon.com/Clear-Plastic-Envelope-Bags-A7/dp/B004O2ERF4
As it so happens, I've recently tested out a few different envelopes. The finest I've run across thus far are these Clairefontaine triomphe small envelopesthat I purchased at Goulet Pens. They are thick, smooth, and lined on the inside with white tissue paper. Not cheap: over $10 tor 25.
A close second, but much more cost effective were these Azaza envelopes on Amazon. No tissue paper lining, but thick, smooth, and for $13/100, a real bargain.
There's part of me that just wants to snap up as many of the Clairefontaine as I can fine but I'll probably stock both and use the Clairefontaine for my most valuable mail. If you're in the US, I'll send you samples of each of you'll message me your address.
Sorry but I want to jump in and disagree with this advice. Plastic bags are never going to preserve scales as well as glassine its hard to prevent the staticic electricity problem and the lack of rigidity compared to glassine can mean accidentally damaging specimens. Fact is glassine is already cheap. Decent pair of tweezers from cvs will never do as good of a job as spade butterfly forceps. These are not expensive items but make a world of difference for prepping specimens. Good tools for any hobby or job make a huge difference.
I know hard when you can't afford a whole kit, but if you collect tools one at a time when you can afford them its worth it to spend an extra dollar here or there
For butterflies the best way to dispatch them is buy pinching their the thorax right beneath the wings. It takes some practice to get the pressure right but once you do it it works every time.
For moths I see different opinions. it can be hard to get them into something while they are alive that will be able to be frozen later. They flap around and the wings can become damaged. I have satisfactory results with Ethel acetate but sometimes it will break down fatty tissue and cause the specimen to be greasy.
Ethel acetate and a kill jar is an invaluable tool in my opinion for all kinds of specimens, especially beetles. Its worth experimenting with different ways to kill, it takes time to learn.
Amazon! I didn't want to use the plain white envelopes that came with my invitations, since they are white. My friend is addressing them with beautiful calligraphy and I am using the Love USPS stamps.
https://www.amazon.com/gp/product/B00RKQZCN2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
I feel your pain and went searching on google. Regular A7 envelopes will work. You can find them on Amazon here for like $15.