So, this idea is neither new nor original. I actually found the idea on Arf.com when I was searching "where to buy silica gel packs".
After messing around with various sizes and ways to seal the filter, I ended up using a whole filter and a stapler to close it shut, just how it said to do it on Arf.com

"Pinos, always trying to re-invent the wheel".
Items needed:
1. Cat Litter, clear type made from silica gel
2. Coffee filters
3. Stapler.
I first pre folded the opening, making 2 folds - each approx 1/2" wide, then I filled the filter to with the silica gel to what I deemed enough. Remember you still have to fold the opening shut and staple it. Trial and error comes into play here. Lastly, I stapled them shut and put a date on them.
The bag of kitty litter was $15 from Pets Mart and the filters and staples I had laying around. I should be able to make hundreds upon hundreds of these packs from the bag of litter. Considering Amazon.com wanted around $10 -15 for 30 x 10 gm packets, this is a cheap, inexpensive way to make silica gel packets for ammo cans, safes, boots or whatever have you.
Thanks for looking.