There are herein disclosed a novel metallocene compound represented by the formula 1 and a process for preparing a polyolefin comprising the step of polymerizing an olefin in a catalytic system including the metallocene compound. The nuggets are sequentially formed by sequentially projecting the laser beam onto the irradiation regions that respectively correspond to the nuggets. Other embodiments are described and claimed. The ink is an admixture of a colorant, and an unsaturated component such that the inks have a maximum of 10% volatile components. A spring may be included to bias the cover in the closed position.