For many RF and microwave applications, a balun is imperative to ensure the proper performance of a balanced structure that is connected to an unbalanced structure. Sleeve baluns are a common type of balun that are relatively cheap and basic, but they are also large, heavy, and time consuming to assemble. This works presents several novel methods of using additive manufacturing techniques to mitigate all of these issues. First, a methods of 3D printing basic designs to reduce weight and improve ease of assembly is presented. This method is then used to construct balun with up to two folds, which reduces the overall size of the balun with each consecutive fold. Next, a castable silicone is used to also reduce the overall size of a balun by reducing the effective wavelength on the balun’s interior, which is first tested with traditional unfolded baluns. This method was then combined with the folded balun design to compound the size reduction from both methods. A final method of printing a dielectric core and applying metal to the core is then presented. The performance of all of the baluns is presented and discussed and future improvements are addressed. Ultimately, this work establishes a method of drastically reducing the size of sleeve baluns to a point where they can be used as in line components, while still maintaining performance levels comparable to a standard, bulky sleeve balun.