Here are some easy to make task ideas for math skills. These are not only great for students with Autism, but for all students. It allows them another way (that looks like fun) to practice much needed skills.
Skills: counting by 1's with fine motor that requires handling small Legos which means getting those fingers working on fine motor objectives
Skills: addition facts using touch dots. Large index cards, velcro, and laminating film...makes adding more interesting then a worksheet.
Skills: recognizing money by name and value. Designed for a student who can read.
Skills: Reading, money name and value
Even if these are not EXACTLY what your students need, they might steer you toward an idea for your students.
Leave me a comment with a link to your ideas!