1 x handheld mains powered drill (I use Dremel 3000).
1 x Dremel chuck (if using Dremel drill)
1 x Dremel multifunction extension (optional)
1 x shallow plastic bowl (about 2 inches high)
1 x thin square piece of wood to fit inside your plastic bowl
1 x diamond tipped drill bit (I use hollow drill bits, they go through the stone faster)
Make sure the pebbles you wish to drill are not too hard, so sedimentary stone is best, avoid harder stones, simply speaking, stones that are flatter and absorb water when it is placed on them will be softer, more porous, and easier to drill.
Also, water and electricity do not mix, so you can buy an extension for your Dremel drill that keeps the actual drill away from water, that is not to say you cannot drill direct with the drill in your hand, you can, I have drilled many pebbles this way; but there is a small risk associated with doing it this way!
1 Place the piece of wood in your plastic bowl, the wood needs to be thin enough to allow you to pour enough water into the bowl to enable you to slightly submerge the stone you wish to drill when placed on top.
2 Fill your bowl with water until it covers the wood when submerged and leaves enough water on top to also cover the stone slightly; a few millimetres is enough.
3 Turn your drill on to a low rpm setting (I use the second speed on my Dremel), a low rpm setting is much better for drilling pebbles. Hold the stone steady in one hand submerged in the water and put your rotating drill tip at a 45 degree angle, and gently make a little starting 'nick' in the stone where you wish the hole to be.
4 Once this is done, drill slightly more at this angle, and then move the drill to a vertical 90 degree angle in a smooth motion. This takes practice, so try it on a few stones you do not mind possibly messing up first!
5 Once at 90 degrees, you are ready to start drilling through your pebble. Without pressing down on your drill, allow the drill to start going through your stone. Notice that a cloud of debris will start spiralling away from the stone. This is perfect, and tells you the stone is soft enough to drill through.
6 Keep the drill vertical and allow the drillbit to do the work, and go down through your pebble, periodically remove the drill bit from the pebble to allow water into the hole you are making.
7 When you have drilled right the way through your pebble, you will feel the drill bit pop out of the bottom of the stone, and into the wood below.
8 You have drilled your first pebble!
Thinner drill bits go through stone faster, so if you do not have hollow drill bits you can use a 1.5mm drill bit first and then redrill with a 2.5mm bit, or 3mm bit, this is much quicker than initially trying to drill the pebble with a wider drill bit.
Hollow drill bits work quicker, and a lot of the time, if you have a hollow bit, you can go right ahead and drill straight through with the hole size you wish to create.
Drill bits get blunt quickly, so do not be alarmed if your drill bit only makes holes in ten to fiteen pebbles before becoming blunt; this is normal!
Empty the water from your bowl after drilling 3 or 4 stones, you need clear water to see what you are doing, and also to see the stone debris spiralling away from the stone, so you know that the drill is doing its job correctly.
That is all there is to it, it does take practice to get used to the feel of doing the steps above, but once you are used to it, you can expect to drill through a dozen stones in an hour depending on thickness, if they are thin (under 5mm) then this figure will be higher.