Identical plastic hemispheres are first treated with organic solvent, which is smeared by a pillow of microporous silicon rubber to achieve a slippery surface upon the hemispheres. The slippery surface upon the hemispheres may comprise a layer of melted plastic. Hemispheres are then placed under an application chamber, where hot gas under pressure softens, deforms and transports a sheet of marker foil over the hemisphere. Two hemispheres are then joined together by use of asymmetric voids and a clip pin inserted, while under compression, into the hemispheres.