Here is how we made our Violet Costume
(more photos below)
It's bascially a battery-operated inflatable Halloween costume with a dress over it.
For the basis of the suit we purchased an inflatable Halloween costume like this:
http://www.buycostumes.com/Inflatable-Ballerina-Adult-Costume/31977/ProductDetail.aspx?REF=SCE-froogle
We had a ballerina outfit, but anything adult-sized and inflatable will do
since you won't actually see it. Tourist, sumo wrestler, etc. There's a bunch out there. Also check with the kids in your cast - someone or their friend or sibling might have worn some kind of inflatable Halloween costume and has it stashed in a closet at home.
Violet put that on first.
Over that she wore a fitted long sleeve tee shirt (Walmart), stretchy fitted shorts (Walmart) and very long, thigh-high white socks (Sears) - all very inexpensive and widely available pieces. The socks covered the inflatable costume and prevented the legs of the suit from inflating, which forced more of the air up into her body area to make her appear larger.
Then I purchased the largest dress I could find (Old Navy, a "maxi-dress"). It had to be as lightweight as possible because otherwise the weight of the fabric would have prevented the inflatable suit from inflating. But extremely lightweight fabrics created static cling when placed against the inflatable suit, which are usually a sort of nylon/parachute fabric. We had to find something just right.
I don't sew well and I didn't have the money or time to hire a seamstress, so we got something this style in a solid color and in a size 3X...and since Violet was a tiny 11-year-old, that's quite oversized:
http://www.walmart.com/ip/No-Boundaries-Juniors-Jersey-Maxi-Dress/8206175
I took the dress in to make it fit around the bustline and cut off the
excess length - no need to hem as it was jersey knit and wouldn't fray. Then we threw it over her shorts and shirt.
We had to cut a tiny hole in the dress for the inflatable costume's air
vent, without which it wouldn't work.
We had to try to make the dress look smaller/thinner for the first half of the show, so I concealed the excess fabric of the skirt area by tying a large sash around her waist and
folding the fabric neatly under the sash. If we hadn't the dress would have looked voluminous and billowy all throughout the early scenes and there wouldn't have been enough
contrast between "regular" violet and "inflated" violet.
When she was backstage just before the blueberry scene she took off the shorts underneath (which freed up more of the inflatable suit to actually inflate) and she took off
the sash.
At some point during the song we had Mrs. Beauregarde grab her around the
neck area and turn on the inflatable costume's switch, which was near
Violet's neck and concealed under her clothes. Are you familiar with the song yet? They sing, and then there is a break in the middle for dialogue with underscore..."mmm, it's delicious, so tender & juicy!" Somewhere in that dialogue we had Mrs. Beauregarde add, "You musn't chew it any longer, spit it out now" to give her an excuse to hold onto violet and flip the switch.
As she sang, it inflated. Easy, but effective.
We did not go with the matching jumpsuits like the Johnny Depp movie had. I simply couldn't figure out a way to get one to inflate properly.
By sheer luck we had access to a suit for Mrs. Beauregarde that matched the color of the dress we made for Violet. If you do want these two characters to match, I would suggest making the Violet dress first and then finding an outfit for Mrs. B since the inflating dress has to fit so many criteria and Mrs. B's outfit can really be anything. You might even be able to buy the exact same dress in the child's regular size for Mrs. B. and in a super plus size for Violet.
Hope this helps!
Kelly Wisneski
Holy Spirit School
Pequannock, NJ