ADVANTUS-Tim Holtz Idea-ology Mask Sheets. A mask is a reverse stencil: instead of a design cut into a flat surface; a mask is a complete shape and you would use inks; paints or other mediums to color around it. Use these blank mask sheets to create your own mask by tracing a design and cutting it out or use your die-cutting system. This package contains two 11-3/4x5-7/8in sheets. Imported.