Another project I worked on recently involved Unit Conversions ('Eaches' to 'Lbs'). This one was a tricky one because I wasn't sure how each unit would convert to another unit! There could be a lot of potential conversions that would have to be made.
Fortunately AX can handle of that for us. On the Unit conversion form:
The User will set up the conversions via this Form and that will determine which conversions can be made and how they are made.
When writing your modifications you can use the UnitOfMeasureConverter class that has methods of CanBeConverted and Convert. Before converting the unit, simply check if it can be converted!