So, here's an eyechart.
d100 through d3 Conversion Chart Without Delta (PDF)
Pretty sure I succumbed to Chart Madness somewhere around d14, so, excuse any errors.
What this should serve as is a conversion table to get from some X in Y or percentage chance on one die to another.
For example, if I'm looking at a table where a Thief has a 35% chance to Hide in Shadows at 5th level, I know that's:
- 11:30 on a d30 (or 19+)
- 8:24 on a d24 (or 16+)
- 7:20 on a d20 (or 13+)
- 6:16 on d16 (or 10+)
- 5:14 on d14 (or 9+)
- 4:12 on d12 (or 8+)
- 4:10 on d10 (or 6+)
- 3:8 on d8 (or 5+)
- 2:7 on d7 (or 5+)
- 2:6 on d6 (or 4+)
- 2:5 on d5 (or 3+)
- 1:4 on d4 (or 3+)
- 1:3 on d3 (or 2+)
I attempted to minimize the delta for each die percentage chance from the "master" d100 chance - for example, from that 35% chance on the d100, 2:7 on d7 is 28.57%, a 6.43% difference. If I would have called that 3:7, it would have been a -7.86% difference.
I made no attempt to "smooth" this conversion by minimizing the rate of change - for example, from the d7 break on 2:7 and 3:7 -
3 42.86% -6.86% (from 36% on a d100)
2 28.57% 6.43% (from 35% on a d100)
That's a ~12% jump. I may have been able to smooth that out a bit by moving the change from 2 to 3 around, but I would have deviated a lot more from the d100 chances.
I will say one thing - the odd dice from DCC make me sad, since there's no 25%/50%/75% markers.