Hello SignWho,
There are several ways to achieve the result you want.
Magento allows you to create different types of products (we've covered the differences in this blog post).
1. You can create a simple product with custom options. That is if you don't really need to keep track of the inventory for each product option.
At the same time, if you want to allow clients to type in letters, choose font, size and outline in an interactive manner, we have the Custom Product Preview extensions that allows to do that in Magento. You can take a look at the demo (there is a link on the product page) and see whether it does what you need.
2. You can create a configurable product with sets of parameters. For example, your product would be the Letter. It will have such attributes as font, material, finish and mounting. This option will work well if you'd like to track the inventory for each product configuration.
We'll be happy to answer any questions you have!
The Aitoc team
Aitoc is a group of distinguished web developers that have been building for Magento since 2009.
See our extensions for Magento 2.