Soft (chalk) pastels - How hard would it be to make just a few?

I got a new set of pastels the other day from the thrift store,  but, it's missing my most loved and used colour.



It got me thinking.  Chalk pastels are made from gum Arabic (i have some powder), pigments (i have some yellow ochre)  and possibly other ingredients like calcium carbonate (i have some).

Does it have to be a big batch, or can I make one or two pastels?  

The recipes I can find seem to be for lots.  They do look fairly easy, but time consuming.  

Anyone here got some ideas?