I made the second skullholder this weekend.
For the first one, I used an H hook.
For the 2nd, I used a G.
Yes, I did this on purpose. I wanted them different sizes.
(because I have multiple sizes of pans, that's why!)
But I thought it would be fun to show you how much of a difference in size you can get by changing hooks:
On top is the G hook model. The bottom was made with the H hook.
There is a good inch of difference in height, and around 1.5-2 inches different in width.
Keep in mind that the actual amounts of difference will vary with your tension and crochet style, but there WILL be a difference.
Use your new knowledge for good, not evil.