Shell for a nerf rival round compatible with Aogist LED balloon lights that can be found in the link below. Print the shell, press fit the balloon lights into the shell and you're ready to go.

https://www.amazon.com/dp/B0CGZXQG66/ref=twister_B0CK4NC8Y2?_encoding=UTF8&th=1

These rounds are only compatible with springer rival blaster and will not work with flywheels. This is because the gap between the flywheels is less than the height of the LED and it cannot be squeezed through. It can only be guaranteed that these rounds work for the Nerf Roundhouse as it is the only blaster these rounds have been tested on.

Caution Because these rounds are heavier and stiffer than a normal Rival round they don't fly as far and will hurt on impact. Use eye protection while using.