11 2 0 180 90 3 4 5 8 9 10 Scriber Level Stock head Protractor head Center head Figure 4-4.  Combination square.  Figure 4-6.  Rivet spacer. Figure 4-7.  Scribe. Figure 4-5.  Divider. Scribes Punches aluminum. Make the layout on the protective membrane if it  is still on the material, or mark directly on the material with  a fiber-tipped pen, such as a fine-point Sharpie$^{®}$, or cover  the material with masking tape and then mark on the tape. A scribe is a pointed instrument used to mark or score metal  to show where it is to be cut. A scribe should only be used  when marks will be removed by drilling or cutting because  it makes scratches that weaken the material and could cause  corrosion.  [Figure 4-7] Punches are usually made of carbon steel that has been  hardened and tempered. Generally classified as solid or  hollow, punches are designed according to their intended  use. A solid punch is a steel rod with various shapes at the  end for different uses. For example, it is used to drive bolts  out of holes, loosen frozen or tight pins and keys, knock out  rivets, pierce holes in a material, etc. The hollow punch is  sharp edged and used most often for cutting out blanks. Solid  punches vary in both size and point design, while hollow  punches vary in size. 4-5