Recently a forum I frequent had a thread come up talking about the essential "junk" we need (or think we need) as magic-workers. Eventually thread drift brought the topic over to the discussion of materials. Specifically - Plastic.
I refuse to use plastic for anything "important", because it doesn't work for me. Plastic won't carry a charge. I can cram as much energy into it as I like, and very shortly thereafter that energy is gone. In ritual, the energy won't carry for the purposes of working.
I could have a knife with a plastic handle, but it would redouble my work. I would have to do the physical cutting and -then- direct energy into whatever it is and that's just not efficient enough for me. It also may not be correct for the way the working needs to be done.
Some folks say that plastic is "unnatural", and "Manmade" and therefore it has no place in Craft. That's not my reasoning. Every material I use in a circle is shaped by man, if not outright created by us. Metals are mined, smelted, refined, and their composition modified by alloys and additives. Steel is no more, nor less, manmade or natural than plastic, seeing as it goes through the same kinds of steps before it's final form. It would not exist without Man's involvement, nor would glass, ceramic, candles, cloth... etc.
"But plastic parts end up in rituals anyway. Lighters, bottlecaps, the paint on statues, or resin statues themselves!"
I don't generally use lighters. Especially not in ritual. I use matches, or kindle off of a sanctum lamp (which is started and rekindled from the sun, or a bowfire). Though, I do use plastic tubs for my crystals, specifically because they're so damned handy at blocking any other energy from messing with them.
I generally prepare my oils, herbs, and others before-hand. I have a collection of mise en place dishes and bottles, all in non-plastic materials. Candles are the great exception here, as are acrylic paints on some of my statuary. However, the statues don't have to function, they just sort of have to be there.
Perhaps this is a personal shortcoming, this "plastic ain't happenin'", but if it makes me stop and consider more carefully the make and composition of my tools... it's a shortcoming that I'm willing to accept.