The number and order of reflection peaks that a poly(N-isopropylacrylamide) microgel based etalon exhibits can be selected by varying the diameter and/or softness of the microgels that the etalons are constructed from, which affects the dielectric thickness. Larger microgels yield etalons with multiple peaks, while relatively small microgels yield etalons with only one peak. The resulting spectra for each device closely match theoretical predictions.