Ask your trimmer or farrier for one of their "old" rasps. They go through many each year and need fresh sharp ones. The "old" ones are still good enough for us to file down a chip or round out the toe a bit.
A farrier's stand for those who like to touch up between trims or the brave ones who can do their own trims.
Inexpensive and easy - this stand costs around $15.
I used 3/4" outdoor plywood 2 1/2 feet by 2 foot. Offset the center so I could stand on the end to prevent my horse moving it, if necessary. Also prevents tipping.
A pipe flange with 4 screws secures it to the base. I used 1" pipe fittings. Any home improvment store will carry the flange and a variety of "pipe nipples" (sorry, that's what they are called). You can get a several different heights to suit your horse's comfort and needs - from 1" to 15".
A tennis ball, cross slit, fits over the top.
The "cradle" was made from a pvc pipe - same 1" diameter fitting - cut in half. I screwed on a piece of thick leather and it screws on and off easily. The cradle was an additional $9.
A good way to keep your thermometer ready for action! Put a dab of vaseline in the bottom of the case, it comes out coated and ready for use. Also keep a small sanitizer with your thermometer to sanitize it before returning it to the case.
Know your horse's normal Temperature, Pluse and Respiration. Over the course of a week, take your horse's TPR and make note of it each day. Take it at the same time and under the same conditions. You are looking for their normal status. Some horses tend to run higher temps, some faster or slower pulse, etc. If you know your horse's normals, then when they seem "off" you'll know right away if things have changed.