On my to-do list is trying to get my daughter's Girl scout badges on to her sash. She has been a Girl Scout for over 3 years now and I have tried many methods. For the most part the badges come with an adhesive on the bag that sticks it to fabric. The only problem is that it doesn't stay. I have also tried a version of stitch witchery, and fabric glue. These stayed for awhile but have eventually come off too since there is a lot of movement and crumpling of said sash.
I did a search of the internet and really didn't find any sewing advice of Girl Scout badges. These badges are fairly thick and have parts that could break a sewing needle. This picture above shows the back of the sash, some badges and thread. On the front I hand sewed the flag because it was thick all over,so I did a slip stitch on the sides. I happened to have white, brown, and green thread so I used those for the Journey and Try-Its badges. I just used one pin to keep them in place and removed it after I sewed one side.
For the back, the badges were a lot of different colors so I decided to use clear nylon thread. The one that I had was from Coats & Clark. It is only slightly stretchy. I haven't used it in awhile and if the fabric is light you will need to reinforce the fabric because this thread is strong. At first I threaded it to a metal bobbin but it didn't go on so great, so I took that bobbin and threaded a plastic one and it worked better.
In the top picture the big blue badge is sewn on with the nylon thread and the ones under a pinned in place. This picture above shows the backside of the sash. The top is the white thread from the American flag badge and below it is the nylon thread holding the big blue badge.
Now I won't be embarrassed at my daughter's plain sash compared to the other girls in her troop. She has been at all but one meeting and has the badges to prove it!