I like the gas cap idea but I think I could make it myself. The floor mats are really nice. The ones that don't say "SI" might be the best reproductions of the OEM floor mats that I've ever seen. They also had a unique cup holder. Have you seen any other aftermarket items like these? What, where?
I also found a rubber insert for the dashboard that looked interesting on another web site. Its nice that people are still making new stuff for these cars 30 years later

 

Floor mats look decent.

You can do the Gas Cap with OEM parts, double sided tape and shave the clips on the back, you can also find them in Integra's and other cars.

Take this part number to the local Honda:
74423-SP0-000
Or buy online:
​​https://www.hondapartsnow.com/genuin...3-sp0-000.html

 

I have the set of mats in my EE wagon, they fit good and feel thick. Have not used in heavy snow/rain yet.

Also have the 3d printed cup holder that goes in the cigarette power port, works well so far.