Hi Darren,
Drawer sides between 12 and 16mm,drawer fronts 3 to 4 mm thicker but usually I make them 19mm. Height of drawer fronts I get from the following formula:
A/ Determine the height the drawers will cover, either internal cabinet or overall cabinet for lay on type.
B/ Number of drawers required
C/ Desired height of smallest /top drawer
Dimension A minus total of gap allowance ( less dust board rails if inset)
Multiply B by C and deduct from previous answer.
Divide this by number of increments. These are determined as follows;
Drawer Increment
1 or top 0
2 1
3 2
4 3 and so on
4 Drawers 6 total Increments
Drawer 2 is therefore top drawer height + 1 Increment, drawer 2 Top drawer + 2 Increments and so on.
As there are 66 increments in total for twelve drawers I have an Excel calculator for it. If you use this system during the design stage it can be tweeked to suit your eye but works out quite aesthetically.
Hope it is of use, Rob.