Model construction falls roughly into 4 categories:
Traditional balsa wood, cut and glue; or composite balsa and foam.
Foam sheet, cut and glue; or prebuilt adapted RC models.
New and possible inthe future , 3D printed models.
Prebuilt scale foam RC models, converted to controlline.
It's worth noting that some of the highest scoring models have been all foam untra lightweight. Overall weight always plays a considerable part in good low speed scores.
Most of the plans available from this site are for traditional models. However there is nothing stopping anyone from adapting any of them to be built with other materials.