Supersize This!

Do you think it would be possible to upsize this vest to an adult size? There are sizings for up to a 7 year old. Could I use a heavier weight yarn to size it up to a woman's 6?

Obviously I'm going a little nutty. I need one more project like I need a hole in my head. I'm working on the first of two Sidar Shrugs for the girls to wear in a wedding this fall. Addie's shrug is coming along nicely. It's actually going very quickly. I'm a little worried about doing 2 that are exactly the same. However, I decided (very wisely I think) to work the larger of the two shrugs first. That way the second one will go that much quicker. Or that's my theory anyway.

I'm also working on spinning up some wool so that I can empty my bobbins. (And practice spinning thin yarn!) I need 4 empty bobbins for the spinning class at Sock Summit. I actually only have 3 bobbins, one of which is partially full. So... a spinning I will go. I'm hoping to take the wheel "camping" with us this weekend.