(See the Bento Decoration master page  for my general thinking on decorations.)
I don’t like to use wieners their relatives very often, though living in a Germanic area of Europe we can get pretty good ones that aren’t dyed a bright pink and actually contain real meat. But once in a while they do appear in my bentos.
You can use a finely ground sausage of any type: wieners, frankfurters, Lyoner, Cervelas, etc. Chicken, turkey, fish even or vegetarian franks should theoretically work, as long as they are flexible enough Try bending one; if it snaps it’s not going to work for this., though you could still use it for cut shapes. The sausage has to be cohesive with a rubbery texture. Coarse ground sausages won’t work.
‘ve seen these gerbera-like wiener flowers on Cookpad  and other Japanese sites a few times. They do make a bento quite festive, and are quite easy to make. (And you know, I’d rather have flowers than miniature octopuses or crabs…)
So here’s an exhaustive step-by-step for your enjoyment.
The basic tools: A small sharp knife; cocktail sticks; and a wiener. To make two flowers, you need 1 whole wiener and a bit of another.
Cut one wiener in half, lengthwise, down the middle.
Here it is, flayed open and vulnerable.
If you have chosen a fairly naturally made wiener, it should have a slight curvature, like this one. Place one half cut site down on the cutting board so that it curves away from you.
Make small cuts along the wiener, as illustrated. Be careful not to cut all the way to the other edge.
Here are the two halves with the cuts finished.
Cut two small vertical slices from another wiener, like so.
Make small, shallow cuts on the surface of each small wiener round in criss-cross fashion. When you are done it should look like this.
In the meantime, bring a small amount of water to boil in a pan.
Now you need to fit the ‘petals’ part around the ‘flower center’ part. As you can see, the ‘petals’ are a tad long, so you need to trim it a bit to fit.
Like so. (Hmm, my fingers look suspiciously sausage-like, or is it the other way around…)
Pin the ‘flower’ together with cocktail sticks. I find I need two: one to pin the ‘petal’ part closed, and another to skewer the ‘petals’ to the center. Be gentle here and try not to break the petals!
Boil them for a few minutes to set the shape. When the cuts in the center part have opened up a bit they can be taken out.
You can use the boiled ones as-is, but I like to put a little color on them by panfrying them briefly.
Well, it took me about 15 minutes to make 4 flowers, using 3 wieners. Your results may vary. Practice, practice.
I chop up the extra bits of leftover wiener and put it in the bento the flowers will adorn, as I did in Bento no. 13 .
If the bento box gets shaken around a lot the flowers may fall apart, so you could leave at least one cocktail stick in. If it’s for a kid’s bento though I would take them out for safety. (Spaghetti pieces are used as ‘edible’ skewers sometimes - this works if you boil the wiener flower until the spaghetti is cooked.)