Duct Tape

Another suspension technique involves the use of duct tape. A long strip of duct tape is wrapped around the bar over the sandbox while also wrapped around the mandrel. Using gravity, the mandrel is left hanging inside the negative cast.

Thick Plaster

Thicker than normal plaster can also be used to suspend a mandrel. This is done by allowing the plaster to cure inside the negative for a few minutes. While it is still somewhat fluid, but firm, slide the mandrel into the plaster. If it is set enough the mandrel will stay where you set it. It is best to observe the curing process the first few times you try this to ensure that the mandrel does not slowly slip out of position.

The two central mandrels are suspended in thick plaster. This tends to work best with small or aluminum mandrels because they are lighter and less likely to drift.