Boy, this makes me think back to 1e... there were lots of odd dice ranges occasionally needed (especially for random scroll generation!)- d16, d32, d40... even the d30 started out this way!
You can generate any of these with 'normal' dice.
d16? Roll 1d8 and 1d6; if the d6 comes up 4-6, add 8 to the d8.
d32? Roll 1d8 and 1d4; if the d4 comes up 2, add 8 to the d8; if it comes up 3, add 16 to the d8; if it comes up 4, add 24 to the d8.
d40? Roll 1d20 and 1d6; if the d6 comes up 4-6, add 20 to the d20. And so on.