Formal/Artistic:
* Portfolio - This is a common choice for a collection of drawings, especially if they are meant to be showcased.
* Series - This implies a set of drawings that are connected by theme or style.
* Collection - This is a general term for a group of drawings, but it lacks specificity.
Informal:
* Set - This is a neutral and widely understood term.
* Batch - This suggests a group of drawings created together.
Descriptive:
* Gallery - This works well for a collection of drawings displayed together.
* Sketchbook - This refers to a collection of drawings contained within a single book.
Ultimately, the best collective noun for drawings will depend on the specific context and the desired tone.