Looks like a flat crystal, easy to get and replace. You can find the part, as well a press and digital calipers on Ebay. You can also fit a sapphire crystal for few dollars more. The cheapest place to buy is Alixepress if you don't mind a longer shipping time.
The small motor, copy of Foredom, found on any online platform, is perfect. Then an assortment of hard felt wheels, mandrels for paper and small wheel, and compounds.
BTW we have a section dedicated to discussing tools, as well one where it's considered polite to introduce oneself. You may ask mods to move your post using the report flag top right.
OP, please do not transform this piece in a casualty of your curiosity.
You have been given a lot of relevant information but there is a great difference between theory and practice, which you shall discover by learning first on something of small monetary value and that is not part of your family heritage.