This article aims at optimizing Sundanese ethnomatematics learning by improving the modeling and creative thinking abilities of primary school students using teaching materials developed with the Didactic Design Research method. The research subjects involved were first-grade and second-grade students of an Islamic primary school in the city of Serang, Banten with a total of 283 students. The data were obtained using learning obstacles test instrument, Initial Didactic Design and Revised Initial Didactic Design as the instruments. The results of the study show that learning barriers were experienced in the materials of addition and subtraction of numbers. The Initial Didactic Design was revised and developed using Sundanese ethnomathematics learning using endog-endogan and engklek games that resulted in the improvement of primary students' creative thinking, geometry thinking, and algebra.