You didn't give much information as to why your LM1117 is getting heated up. I suspect that you have maybe 12V going in and you are taking 5V output at a pass current that is rather high. If using these numbers and a pass current of 333 mA then the power being wasted in the regulator is (12-5)*0.333 = 2.3 Watts.

These days it is almost (note I did say almost) unacceptable to use designs that dissipate power into useless heat. Adding a heat sink to a design that is already compromised is often a bandage over a wound that fails to heal.

In any case the heat in the regulator is an indication that you may want to address a possibly different type of design. You should at least investigate a small switcher design to make things a lot more efficient and eliminate the useless heat generation.

I can say that experience will teach you that doing things like changing from TO-220 to SOT-223 just to reduce cost and then turning around and adding cost by kludging in a heatsink with some type of custom solution is really a folly even if you choose to ignore concerns about useless heat generation.

Michael Karas