Elizabethan collars are clear plastic cones placed over the head of an animal in order to prevent them from scratching or licking a wound (see 3rd picture). Although E-collars are effective they can also cause the animal a lot of stress. E-collars limit peripheral vision causing the animal to run into a lot of things and also make it harder to eat and drink. This instructable offers an alternative that is cheap, easy to make, and will work in most of the situations that one would use an E-collar.
Warning: This collar is designed to give an animal more freedom than an E-collar and therefore cannot be used in every situation that an E-collar is used. In particular, it may not prevent an animal from licking/biting its front paws or the end of its tail. However, with cats (and some short faced dogs) it will prevent the animal from using its front paws to scratch its face. In any case, you should always watch your pet for a while to make sure this collar works as intended.
Step 1: Materials
1. Foam pipe insulation: This is the insulation used to keep pipes from freezing in winter. It should be fairly ridged foam and should defiantly not be fiberglass. What matters most is the outer diameter (O.D.). However, insulation is generally measured by the inner diameter so take a measuring tape. For my small to mid-sized cats I used foam with an O.D. of 5cm (2in). This size prevented one cat from licking or biting her hindquarters and prevented another cat from scratching her chin. For a large cat you should have 6 cm foam. A large dog would likely need foam with an O.D. of 10 to 15cm.
For large dogs you may want to fill the inside of the foam with cloth or smaller diameter foam so the dog can't simply crush the collar.
2. Electric or other plastic tape. The kind of tape you use is important as the collar is inevitably going to have contact with whatever your pet eats and drinks. I tried cloth athletic tape first and within a couple of days I had to negotiate terms with the colonies of bacteria that had seized control of the collar.
3. Shoelace, or other thick piece of string.