I recommend the use of acrylic resin or plaster, also with polyurethane resin.
You can glue the boxes onto our modular MDF wooden bases to get a portable field or start building a huge stadium on a foam base or thick wood.
The precision and fit is very good, the joints between pieces are barely visible. Reproductions in polyurethane resin may slightly alter the accuracy of the fit and wear out the mould after many copies.