Purpose: To investigate the effects of different post-curing units on chemical properties (degree of polymerization) of 3D printed resins to determine whether less expensive alternative post-curing units can be a viable alternative to the manufacturer’s recommended units. Methods: Forty-five samples were fabricated with an LCD printer (Phrozen Sonic Mini, Phrozen 3D, Hsinchu City, Taiwan) using MSLA Dental Modeling resin (Apply Lab Work, Torrance, CA, USA). These samples were divided randomly into four different groups for post-curing by four distinct curing units, the Phrozen Cure V2 (Phrozen 3D, Hsinchu City, Taiwan), a commercial acrylic nail UV LED curing unit (SUNUV, Shenzhen, China), a homemade curing oven fabricated from a readily available UV LED light source (FastToBuy, Shenzhen, China) and the Triad® 2000™ tungsten halogen light source (Dentsply Sirona, York, Pennsylvania, USA). The degree of conversion was measured by FTIR spectroscopy using a Nicolet 6700 FTIR Spectrometer (ThermoFisher Scientific, Waltham, MA, USA). Results: The Phrozen Cure V2 had the highest overall mean degree of conversion value, 69.6% with a 45-minute curing time. The Triad® 2000 VLC Curing Unit had the lowest mean degree of conversion value at the 15-minute interval with 66.2% and tied the lowest mean degree of conversion at the 45-minute interval with the Homemade Curing Unit, both with 68.2%. Conclusion: The type of light-curing unit did not yield statistically significant differences in the degree of conversion values. There was a statistically significant difference in the degree of conversion values between the 15-minute and 45-minute curing interval. When comparing individual light-curing units there was a statistically significant difference in the degree of conversion for the Phrozen Cure V2 between the 15-minute and 45-minute curing time (p = 0.029).