Spirit traps from Protection and Reversal Magick by Jason Miller. These are made out of birch and are 7" in diameter. These are approximately 3/16" thick (1/4" birch ply). Instructions for using these can be found in P&RM.
Birch is a sacred wood best used for cleansing rituals and expelling evil spirits. Those interested in the practice of white magic will find this wood is a wonderful companion, exemplary in healing. Excellent for protection spells. The Celtic wood of the new year and new beginnings, Brooms were traditionally made of Birch twigs. Birch can help you sweep away negative energy, organize and calm the emotions.
Triangles are known to be a very strong sacred geometry that is capable of trapping and containing spirits. We see evidence of this with the triangle of art in the grimoire traditions. You may draw harmful spirits into this trap and bind them in the name of Hekate with her secret names Aktiophis, Ereshkigal, Nebotosoualeth.