The original use for these images is microscope slides. Yep, those same glass slides that you might have used in biology can be repurposed to make lovely pendants. I've had good luck finding the glass on ebay. The slides with ground edges are nice to save getting cuts on your fingers. There's also a shop on etsy that I've had nice interactions with called GlassSupplies who carries pendant glass in 1x3 inches. Robin (the owner) knows a ton about glass soldering and her shop carries all kinds of soldering supplies.
For basics on soldering I highly recommend the book Simple Soldered Jewelry & Accessories by Lisa Bluhm. Lisa runs the company Simply Swank and also has a super-cute soldering starter set (though the customer service reviews on amazon for fullment are iffy, so perhaps try it from Stampington instead). Stampington also has the best video I've found online for soldering basics.
If you're looking for something waaaay more simple, Ranger has a whole line of memory glass with pre-made frames that are super-easy and are available on amazon. You basically cut out your images (they're great double sided), put them between two glass slides, foil tape/glue/sticker the sides closed, the slide it into the frame. Totally my kind of crafting.
I've also seen some really great greeting cards made using the tall, thin images. Plus lovely bookmarks and window/Christmas ornaments.
If you have any examples of crafts you've made with piddix 1x3 images, send them my way and I'll add them here, or put a link in the comments below. I'd love to see them.