Don't rush out to buy a new bathtub because of a minor blemish. Replacement costs are fairly high, costing upward of $300. Repair costs are not as pricey, considering you can pick up a kit for around $20. Acrylic bathtubs have a solid surface, not a sprayed or painted finish. This makes repairs rather easy to do.
Repairing a Chipped Acrylic Tub
Cut out the damaged area of the tub in a V-shape with the utility knife.
Prepare the bathtub repair kit's filler paste per the directions included with the kit.
Put the filling paste on the chip and rub it in with your finger. Try to get it as smooth and even as possible so minimal sanding will be required. Wait an hour for the filler to dry.
Rub with dry #100 grit sandpaper in a circular motion to get the dry filler paste to be even with the surrounding surface.
Wet the #1500 grit sandpaper with water and rub in a circular motion to polish the finished surface. Sometimes the repair kit will come with rubbing compound to be used with a clean cloth instead.
Prepare the paint mix provided in the repair kit per the directions included, if painting is needed. Allow the paint to dry 24 hours before using.