I am not quite sure what you mean with a "thick balloon arch", but here are some ideas:
- Build a Spiral Arch with clusters of 4 balloons.
- Build several Spiral Arches, stack one behind the other and fasten them together
- Create a "Rainbow Arch" by building several single arches of varying lengths and place them together.
- Extra Tip: Use "Link-O-Loons" (or Linkaloons) for the single arches - fill the balloons with helium and knot them together with their especially for this purpose designed ends, you won't need any fishing line or frame for the arches.
