Nothing technical here, you could make it with your eyes closed and your hands behind your back.
Hold the two skewers together and, on each side, thread one of the small nuts. That's all folks!
Depending on what you want to keep straight, a wick or a core candle, slide the nuts closer or further away from each other along the skewers: the closer they are fro meach other, the harder the skewers will be pressed together and the higher the pressure on what is stuck between them will be.
Insert the wick (or the core candle) between the two skewers and between the two nuts. Adjust the pressure using the nuts as explained above.
As you can see on picture 3, this very simple tool makes it very simple to hold a core candle centered in a mold (used here to create an ice candle).
That's it, you've just spent two minutes making an inexpensive little tool that will more than probably help you many, many times...
If you don't have any nuts by the hand, just use a few rubber bands