Please know that I am not endorsing a particular brand of this product. After doing some research online today, I see that there are various brands and types of this product available for purchase both on the web and in some select stores. I just happen to have experience with the following product from The Pampered Chef and have found that it creates an at-home version identical (in my opinion) to the Smucker's brand of Uncrustables. It is called "Cut-N-Seal" and is pretty reasonably priced at $9.50. You lay down a slice of bread, make a little indentation in the middle, smear on your peanut butter and jelly, top with another slice of bread, press down on the bread with the Cut-N-Seal, pull away the edges and you have yourself a cute, little, sealed sandwich! The possibilities of types of sandwiches are endless. I've done tuna and chicken salad inside of hearty wheat bread slices. My daughter likes peanut butter and honey sandwiches made with this. What I really like about it is that I can make these ahead of time in batches, put each one in a plastic sandwich bag, stash in the freezer and throw them in my kids' lunches in the midst of the morning rush! It's great that you can customize these using whatever you like ... you pick the bread and the fillings! Also, I find that sandwiches sealed up this way are a lot less messy compared to traditional sandwiches that contain gooey ingredients like, peanut butter, jelly or honey! And, since a couple of my kids don't like the crust anyways, it works out perfectly! (By the way, since the fillings don't usually come in contact with the crust portion of the bread, you can save the crusts - when making large batches of the sandwiches - to add into stuffings or bread puddings if you don't want to just toss them!)
I, also, plan to experiment with this gadget using pie crusts and pie fillings (sweet and savory) to make mini pies. Although not heart-healthy at all, I have fond memories of my grandparents making individual fried pies in a large cast iron pot on the stove top, as well as mini pies over the open campfire with "pie irons" in the summer. I'm, also, tinkering with some ideas for using this product to make hand-held "grilled" cheeses that would be sealed, obviously, then either baked or grilled like a panini.
But, I really wanted to create this post to allow you all to see that products exist that allow you to make these sandwiches at home. Do some research and shop around. I've even come across ones that produce square sandwiches. Get creative and have fun with it!