Our elementary school's PTO did a crafts day in December. I volunteered to run a table to help the kids make flower pens as gifts.
I was inspired by something received as a bridal shower favor -- that was done with beautiful big fabric tiger lilies and flower tape. My goal was a craft the kids could do for $0.50 or less because, well, it's kids. This is their allowance we're talking about.
I got boxes of pens, rolls of colored tape (we used floor tape rescued from a corporate discard pile), and hit up the local discount stores for off-season flower bouquets. We cut the bouquets up into smaller bits and the kids taped them on. My trick was a narrow piece of tape at the top so the kids could arrange things how they want, and then run the fat tape lengthwise. We trimmed it so the cap could go back on. The kids loved it -- they were able to do it themselves, and they were making all the choices. My favorite thing to say all day was "You pick which (X) you want to use -- that's your design decision!" Their faces lit up.
The only child I saw not enjoying herself was the one whose father was trying to get her to do exactly the kind of pen he would have done...
I should have mentioned since this is for kids, the flower bouquets are usually on wire. You'll need wiresnips, and tell the kids that the cut bits can be quite pointy. You have to work pretty hard to do more than a light scratch, but it's worth telling them.]