Picket Fence Studios 4in x 4in Stamp Set – Jack-O-Lanterns – You’ll be extra thrilled to create Halloween projects with the Jack-O-Lanterns Clear Photopolymer Stamp by Picket Fence Studios. Included in the package is one clear photopolymer stamp on a 4in x 4in storage sheet. The stamp can be used with an acrylic block and your favourite inks (sold separately).