1) Figure out your base chip. T1, T5, T25 (common) ?
2) Figure out your blinds. I typically like like to do multiples of 2-4, 3-6, 4-8, 6-12, and 8-16 of each chip. Possibly adding 1-2 and 1-3 of the first chip to the very beginning of the structure. Then figure out your blind times. I think 18 mins should be the bare minimum to set it so the button goes one orbit per level.
3) Find the end point. So the PCF rule of thumb is the tournament will end when the total chips on the table represent 20bb give or take. So factor in total buy ins (including an estimate on rebuys and add ons if you will allow it.).
In your case, find the bb that hits the 4 hour point, multiply by 20. And divide by the estimated number of entries. So say you figure to play 6000-12000 after 4 hours. That means you want to target a total of 240K in play. So for 32 players, assume 16 re entries, and not allowing add ons. That's 48 entries. Divide 240k by that and you get 5000.
Then all that's left is to plan your chips. Plan your chips for the biggest format you can envision and then the smaller formats should also be accommodated.
So while this is for a short 32 player tournament having T5000 stacks, you could want to plan for longer events with T10000 stacks and fewer players.
For T25/100/500/1000 the 8/8/4/x format (where x is the number of T1000 chips to make the starting stack) is considered the bare minimum. 12/12/5/x is a format to create starting stacks with more chips.
Then it's just a matter of multiplying out your starting stacks, plan extras for color ups and voila.
Good luck.
