Materials run out

When doing Malcolm's part time job, making 2 Mongo's Traveler's Suits (F), I accidentally put the whole stack of finishing threads to make the first one (he only gives you 2 threads), and thus was unable to complete the second one. Is there a way to get more materials? I tried going to Nora to buy more thread but I wasn't allowed to use it.

I doubt there's a way to get more materials, since you can use the materials supplied after you finish the part-time job for skill training. For example, Walter's basic job for cutting cheap leather straps gives 30, and you can keep them after the job is finished for Weaving training.