What is the correct grammar to describe a vast range of things in a list (without listing them off)?

That's not bad at all. Just as you have done you should list not the items but the variety of items; a collection of these from descriptive source and a bunch of those of another kind, singling them out for their disparate forms or origins. What you are highlighting is their contrast and variety.

One popular approach is to list a few items you expect to be very popular, then end the list with "and more". For example, "We grew our collection to include a variety of Makerspace tools and materials to support a wide range of creative activities including modular robotics, sewing, wood carving, and more!"

If your variety is truly dramatically various, consider listing every activity your maker space now supports. "We have grown our Makerspace to add tools and materials for new activities. Visit us to experiment with [full list of supported activities]."

Maybe I'm missing something but why not use e.g. and slightly tweak how the list is presented:

I grew our collection to include a variety of Makerspace materials for almost any use, e.g. modular robotics, wood carving, sewing, and Scratch-based coding units.

From MW.com:

E.g. stands for exempli gratia in Latin, which means “for example.” It introduces one or more examples that illustrate something stated...