Hi Andrew, I've found that quite a few models in Tomoko Fuse's book 'Floral Globes' can be made with sturdier paper and they hold quite well. In general they are two piece modulars with a base fold and a decorative/holding fold. I've made larger versions of one or two of them using 100->120 gsm coloured paper for the base and then choose a suitable decorative paper. They assemble in a similar fashion to Sonobe units (which are also fairly sturdy with appropriate paper) so the assemblies can easily go to hundreds.
Caveat; I haven't tried other assemblies on the Floral Globes yet. The main point here is that some modulars are pretty sturdy with a different paper choice. Dennis P.S. I've also found that a lot of modulars made using edge modules collapse under their own weight when they are made larger or with longer edges.