You can get sodium hydroxide (NaOH) from supply houses. Just google
for places like Flynn Scientific, Sergeant-Welch, or Fischer
If you can research to find out what the ideal concentration is, it
will probably be expressed as some 'molarity,' like a 5M solution. To
mix these kinds of solutions accurately, for each unit of molarity, use
40 grams of NaOH with enough water to make one liter, (about a quart +
2 oz.). So for instance, a 4M solution would be 160 grams of NaOH with
enough water to make one liter. For smaller or larger amounts, just
ratio it down or up. Make you solutions in glass. DO NOT put this in
contact with metal.
It will come as pellets. They must be kept under tight seal. They
will pull moisture out of the air. If you look at them they will look
dry, but if you were to rub a pellet between your fingers it will feel
greasy. The grease is the fat in your own skin being dissolved.
Stray pellets must not be thrown in a garbage can. Just wash them down
the sink. Drano is made mainly of NaOH.