Jim I used a product called Cast'n craft, Clear casting resin. It's available at Michaels crafts.

The IMPORTANT part is finding a suitable tube or shape to cast your parts in. For the domed shaped part I used a pill capsule of the right size. I used a syringe body for the bank indicator. You need something that you can pour the resin into and then you can either push it out or destroy it. That way you'll have a smooth outside wall on your part. Other wise the resin won't be smooth.

For what you want you could use a plastic drinking straw or similar object.
Give it a try, its easy and you'll have exactly what you need.