I have made a couple attempts at supplemental weft. One of them came out rather well and I think it's because I kept it simpler.
This band was a lot of fun to do. If you're looking for something new to try that's easy and fun, I'd highly recommend it.
This band took three extra shuttles. You could use bobbins or some other holding device since they don't need to be used to pack down the weft. But I had plenty of shuttles so that's what I used.
For the outer lines I simply wrapped the extra weft around an outer warp thread. I came from the same direction each time. The weft was only placed into one shed. Another way to state it is I added the extra weft every other row.
For the middle line I placed the weft every row. I went back and forth like with regular plain weaving but only going under the three warps in the middle. This surprised me by creating a braided look.
None of this extra weft is visible from the back of the band.
The most difficult part was figuring out where to set down all the shuttles. They ended up all over my lap and I wasn't able to move very much. Storing it away for the night without tangling them was also fun. But I'm really happy with how the project turns out. Hope you will be too!