He means to say he wants a template which has boxes all over the document since the helpsheet has to be hand-written, rather than software for writing the equations themselves Problem is I don't think there are any such templates around, largely because no one one knows in advance how much space you'll devote to writing a group of related formulae with explanatory notes.
You could use Word to draw text boxes if you want to. The best way to do it is to write it out by hand first so that you'll have a good idea of how much space you'll need for each group of formulae as well as how the layout would be structured. Then draw the boxes in Word. Just draw one box, copy and paste it repeatedly, taking care to resize them if necessary.