Step 1: Supplies and Tools
Whisk broom - black bristles, again from the dollar store.
Craft needles - regular needles may be too thin, so get some heavier duty ones. My dollar store had these too!
Wooden dowel - size that fits comfortably in your hand. You may also use the handle of a wooden spoon, I think the dollar store sells those too.
Small side cutting pliers. Guess where you can get them if you don't have some already? :-)
Small bottle/tube of liquid latex - places that sell Halloween makeup usually have this, so try your pharmacy, department store, or your favourite Halloween store, or possibly even the dollar store - you don't need much.
Gloss Mod Podge or other GLOSS sealant - your craft store should have this, though check at your dollar store in the craft aisle.
Step 2: Tool Construction
Proceed with CAUTION:
On one end, embed the point of the needle into the wood. Try to centre it, and then insert it as deep as you can.
If possible, and you have a small enough drill but, make a little hole first so that the dowel doesn't split. I just used a pair of pliers and pushed it into the wood.
Look at the eye of the needle. Take the cutters/pliers and cut the end of the needle off about halfway through the eye. This will leave you with two prongs.
Step 3: Create the Whiskers
Cut several bristles off the broom, making them as long as you can.
Fold two of them in half to form a V shape (or an upper case lambda character...)
Insert the point of the V into the prongs of the tool.
Step 4: Insert the Whiskers
With the two bristles between the prongs, press them into the desired location on the side of the rat's muzzle. Do this carefully, using just enough pressure to make sure that you don't poke it right through and into your leg/arm/child. hey, I'm all for blood and guts at Halloween, as long as it's not real...spending Halloween in the hospital getting stitches would not be fun.
Press the tool deep enough that the eye of the needle completely disappears into the rat.
Hold the whiskers with your fingers while you extract the tool. If the whiskers come out, just use the tool to insert them again.
Do the other side (unless you plan on having an extremely insane looking rat!).
If desired, arrange the whiskers so they are not grouped all together. (Sorry, real whiskers aren't in multiples of two, they are usually individual, so we have to give the "ilusion" that they are real. Hey, what do you expect for a buck...)
Use a drop of liquid latex where the whiskers insert to seal them in.
Trim the whiskers to the appropriate length if necessary. I'm not sure if all animals are this way, but cats usually have whiskers about the width of their body - this allows them to determine if they can fit through a hole...
Step 5: Other Enhancements
Often these props also have lines from the molds. These may be able to be cut off with a craft knife. Check one on the underside of the prop to see if the underlying plastic is a different color than the prop itself. If so, you can trim these molding lines flush with the texture of the prop. If your cut reveals a different color, you will probably want to leave them - unless you want obvious lines or desire to paint them..
If you have a rat that is hard plastic and appears to be hollow, you can make the eyes glow, sometimes. First, find something that has a red LED on it - a toy, remote control, mini-flashlight, etc., and will fit inside the rat. Cut a hole in the bottom, pour in some of the gloss sealer and spread it around. This will make the insides nice and shiny and will reflect the light better - you can also use white paint as well. Carefully cut out the eyes. Insert the LED into bottom of the rat and turn it on. (Please do not use a light bulb - the heat in such a confined space can be dangerous!).
Step 6: Display
Do this to your other rats, mice, cats, dogs, weasels, etc. As you can see, I've attached whiskers to many of my animals. Sorry, I haven't displayed these properly, yet...