Luckily, hot dogs are very important in bento.
As you can see, there are 'cutters' you can buy that make it very easy to shape hot dogs into cute designs. I have come across octopuses, rabbits, turtles, tulips, fish, crabs, and turtles. There are probably more. You don't have to have mini dogs to use them, you can use regular hot dogs that you cut to size. Once cut, you boil the hot dogs (some fry them), and then once cooled you can put them in the freezer for a month.
If you don't have cutters, just use a knife to make creative cuts. Here are a few tutorials on other blogs you can use to make your hot dogs fabulous:
Hot Dog Sunflower (you don't have to use quail eggs)
I like to make the octodogs and crabs, but I make short tentacles in both cases.
I hope you have fun with it!