Things You'll Need
Variable speed drill
Diamond cutting bits in various sizes (1/8th of an inch as the smallest)
Cloth or rubber mat
Cutting glass is a difficult process and requires some finesse. However, with the right tools it is possible to learn the tricks to cutting glass--perhaps not with ease, but at least with competence. Glass cutting requires the use of diamond cutting bits, one of the few materials that can actually cut into glass. Diamond bits are found at most hardware stores. Safety is the most important issue with glass cutting, even with Mason jars, and it is important to always wear safety goggles and gloves when drilling through glass.
Plan where you want to place the holes in the Mason jar. Do not place any holes within 3/4 of an inch from any edges of the jar, including the bottom edge, or place holes within 3/4 of an inch from each other. This limits hole placement to close to the middle of the jar. Mark the placement of the holes with a permanent marker.
Place the Mason jar on a flat surface. Make sure the jar is well supported, and will not slide around on the surface. Use a cloth or rubber mat to hold the glass still.
Place the smallest drill bit inside the drill. Spread cutting oil over the drill bit. Drill into the glass slowly and carefully. Use constant pressure as you drill through the glass.
Stop drilling just before you break through the glass. Reduce the amount of pressure that you apply on the drill as you drill through the last section of glass.
Replace the small bit with a larger one. Cover the surface of the bit with cutting oil. Drill through the same holes in the same place.
Gradually increase drill bit sizes until you have the hole size that you want for all holes.
Since Mason jars are made of thinner glass, a hollow drill bit, where the cutting edge is placed along the outside edge of a circular shape, can be used if desired. These drill bits may be harder to find, however. Check with your local hardware store.
Mason jars with holes make handy lanterns. The top can be screwed back on after the candle inside is lit, and smoke can still escape out of the hole.
Small animals being kept in mason jars will need air holes to survive.
Always wear safety goggles and gloves when performing all cuts. Tiny glass shards may bounce away from the glass and can get into eyes or hands, causing serious damage.