Sorry for the delay ...
Unfortunately, it is not advisable to use braille dots to try and make shapes -- particularly at this age level.
It would depend on what type of software you have and what type of embosser is available. There are some embossers (such as the Tiger) that can emboss outside of the normal braille cell configuration. Graphic software is used to draw an image which can then be embossed.
BANA is going to be posting the Guidelines and Standards for Tactile Graphics on their website (probably in April). While they are what is considered to be the best solution, sometimes when you don't have the equipment, or the student needs the material immediately, you just have to do the best that you can with what you have. I can only make suggestions. And it sounds as though, in your case, your spur wheel may become your best friend.