Cover the alginate with plaster bandage to reinforce the mold so that it holds its shape when it is removed. Remove the cast and immediately form a vessel by extending the borders with plaster bandage without deforming the shape. Sprinkle talcum powder inside the mold for ease of separation. The orthotist then fills the negative with plaster of paris. Straws are placed in the eyes and nostrils to allow for better seal and replication of those areas.
Plaster is added to the mold at sites where pressure relief is needed.
The plastic is removed and placed over the mold. A vacuum pump device is applied to the model until the plastic is pulled in tightly. The straps are often made of elastic material that can be secured by Velcro. These should be positioned superiorly and inferiorly to avoid pressure on the ears. If pads are used, contact cement or cyanoacrylate glue is used to attach narrow pads of closed-cell polyurethane foam to the inside above the eyebrows and at the cheekbones so that the appliance is not sitting directly on the face.