Carving grooves in pink insulation foam board to cast coil designs seems clever, but it is not practical. You would have to gouge a busy road map of grooves to get much flexibility of design. Or go through a lot of pink foam.
Our next idea is to use strips of aluminum flashing held in position with kebab skewers. We liked our sample above, but found it awkward to position the flashing walls and plunge them into place at the same time. Much easier to position the fences just so and then skewer them into place.
Our solution was to tape little prisms of pink foam to the fences. Now while one hand holds a fence in position, the other inserts the skewers through the pink foam. But first, our sketches. Here’s a couple. The bottom right is the one we went with. While the others seem good, we wanted a girthy design with large open spaces. We use them in our work often as connectors of elements, sometimes putting things through the openings. Another consideration is fragility. Both the top images have necks that stick out without much support. They won’t take much weight and probably would bend and crease with the amount of abuse we give our inventory.
Here is the coil walled in ready to dry. You can see the pink foam forms well in the top right. We used taped clumps of thicker skewers where the opening was too small to be fitted with a flashing fence. The lower left image shows the power of 6 hour abaca to pull against whatever’s set to hold it. To adjust, we removed the skewed, repositioned the fence to allow the shrinkage and then re-skewered.