It's a great concept. Something I would recommend is:
- a checkbox to remove the TM at the end of the logo.
- expanding the color and typography options. For quick prototyping, like the "Lorem Ipsum" of logos, this selection is probably fine. If you add more palletes / colors / icons, you can break the toolbox off into separate tabs.
- Removing the "Product Hunt" badge from the toolbox to maximize the space of the content, and instead putting it in the footer
- (Personal preference): Moving the options toolbox to the right of the screen instead of having it on the left, or giving the user the option to change the layout.