First, I cut a band 4.5" by the circumfrence of the hem, plus 1.5". I hemmed the short edges (3/8" turned twice). I pressed 1/2" under along one long edge. Then I stitched the right side of the band to the wrong side of the pants, using a 1/2" seam.
Next I edgestitched pressed edge down, covering the previous stitching.
Lastly, I ran another row of stitching about 1/2" away, making a casing. 
The finished pants! On to the tunics!
First, I cut 6" strips from the gold. It's a reversible sari fabric, so I hemmed the long edges so the gold bordered the blue (1/2" turned twice). If I didn't have reversible fabric, I would have used a hong kong underlining technique with 2 fabrics. I did 6 strips hemmed on both sides, and 4 hemmed on one side only, for the inseams/crotch seams.
I cut the pants out of the green fabric, and laid the strips on top. Then I basted them to the green, and stitched down the strips to the crotch level, leaving them loose from there to the hem.
Ready to sew!
Next, I cut the diamonds to piece together to make fabric. I tried to think of a way to strip piece this, but couldn't figure it out in my head, so I decided to just cut the diamonds and sew them all together. I cut 4" strips, then laid the 60° mark on the edge to cut an angle. Using that new cut edge, I then placed the 4" mark and cut the diamonds. 
I stitched contrasting diamonds together in pairs (and screwed them up at first), and then laid them out on my pattern, so I would only piece as much as I needed. Then I stitched pairs together, and filled in with single diamonds or triangles. I forgot to add a 1/4" seam allowance to one edge of the triangles at first, so I just kinda stretched those to fit a little bit.
Then I did it all over again, only in reverse. I think the second time around went faster and looks better. I used my serger, since the gold frayed a lot.
Done! This is as far as I got yesterday. Today, I will cut these out and stitch them together. As well as finishing these pants, I also hope to finish the other pants (remember, I am making 2 costumes: one for Caleb, and one for his friend).
On Saturday, I went over to Joann Fabrics and scoured the clearance racks. Calvin was with me, and he actually picked most of these fabrics. He's got a great eye for this sort of thing. The gold is really the wrong side of a blue sari fabric. 
Here's our inspiration. While at the Ren Faire in AZ, Caleb looked in all the shops for jester costumes. He didn't see anything he liked, but he did like the look of this painting, so I took a photo. We searched online for costumes too, but everything we found was pretty lame, IMO. I have been re-reading some Asimov books, and noticed this one had a neat painting on the cover too, so viola! Inspiration! We found the hat pattern on Saturday, though I'm going to see if maybe one of the boys would like a variation on this one (upper right) instead.
It's from one of the last issues of Topkids (you can read the pattern review here). I made it from the rayon/linen blend you can get at Joanns.
It was fun to make. I used a fusible interfacing on the collar and cuffs, and it bubbled, but otherwise, I really like the shirt. I'd make the cuffs wider next time.
The pockets are built into the yoke. 
Check it out! Caleb in the shirt about a month before he turned 7! He's going to be 12 in about 2 weeks; my how the time passes. Calvin is smaller, so even though he's 8.5, the shirt fits him great.
Ravelry project page is here. If you don't have a Rav account, more pix are on my Flickr pages. I used Rowan felted tweed and size 4 needles. They are knit from the top down, so you can easily make them as long as you want. I had plenty-o yarn leftover.
Calvin is a delight to knit for, as he LOVES anything handknit. He has been wearing these All. The. Time. He wants more pairs. He hasn't decided if he wants anything embroidered on the fingers yet.
We watched this guy's show. He holds 4 Guiness World Records with whips, one of which is the most whip cracks in a minute (over 400!). Besides using these fire whips, he also used a whip to crack open a can of soda, sliced celery held by a patron with a really really long whip, and had a chain mail whip which made the loudest crack I have ever heard. It was way cool.
We watched some belly dance troupes. I've been taking lessons since October, and believe me, belly dancing is HARD. It's all about muscle control in your upper and lower abs. 
There were lots of shops. This one had little paddleboats for kids to play with (and hopefully buy).
I took a lot of pictures of just scenery.
Isn't this woman (or man?) awesome? I missed her lecture, but I think it was about styles of dress and makeup in that time. Look at that little traveling dress on her table. I want one!
One of the fun things we did on our vacation was go for a hike in the desert. We went to Ursery Mountain Park, and did one of the easy trails (Connor is pretty slow).
It was so pretty, and a lot of the wildflowers were in bloom. We hiked to the backside of a hill, took a play break on a playground there, and then hiked over the hill to get back to the car.
At the top of the hill, we saw a gila monster! How cool is that?
It was a nice time, and the boys enjoyed the desert.
Another day, we visited Rawhide. Connor (a big Thomas fan) got to ride on a train (twice!), and loved it.
There were gunfights!
Both Caleb and Calvin got to try out the mechanical bull. They also panned for gold and tried some climbing.
My in-laws live in a retirement community, and we went swimming at least once a day. 
Connor loved the pool, although apparently he's mad at me in this pic, as I'm probably not going fast enough for him to catch one of "my boys".
The last day, he finally got comfortable enough to put part of his face in the water and blow bubbles. I had been trying to get him to do that for the whole week!
My in-laws have a few citrus trees in their yard (pink grapefruit, tangerine, juice orange, and tangelo. They even have a key lime tree in their front yard). Every day we picked oranges.
It takes a LOT of oranges to get enough juice for my crew!
Caleb hit on the perfect combination for juice: half juice oranges, half tangelos, with 1 or 2 grapefruits. Delicious!
See that juice pitcher? We went through at least one of those a day, with at least half of the juice drunk by ME! I love OJ, and to have fresh-squeezed every day? Wonderful!
In the afternoon, I had to run some last minute errands before leaving for our vacation. While I was gone, David and Connor got dressed up and went out to play as well. Here they are on the HUGE snowdrift in the park. Seriously, I think this drift was at least 4 feet high. They worked on carving tunnels throughout it, and eventually, this area was crawling with kids. :) 