Resin brushes are extremely useful for "wetting-down" the repair site prior to application of fiberglass cloth or tape. It is very difficult to clean brushes that have been used with resin, so plan on using inexpensive ones and pitching them when you're done.
Brushes can be picked up at your local hardware store, marine store, or home center for a few bucks.
They are available in many sizes to provide a lot of flexibility and even come in assortment packs. Choose the size of brushes based on the size of repair that you're going to be tackling and pick up a few more than you think you'll need!
The cheap chip-bristle brushes (like shown above) are perfect for resin work. Some chip brushes can be found for less than a dollar each, but we've had problems with the SUPER CHEAP ones shedding bristles in the work! Look for brushes between $1 and $2 and you should be fine.
Also, these brushes are ONLY for resins. You will be extremely disappointed if you try to paint with these things -- Trust me.Go back to Fiberglass Tools from Resin Brushes