I use them round 3MM & 5mm LED lens holder from Aliexpress.com for my trucks. They give the rounded appearance, & the black holders look like the rubber grommets that hold the lights in place. You'd need to use a red LED, as the clear bulbs would be slightly showing. HOPE this helps!
edited to add this URL
https://www.aliexpress.com/item/3244...rch-mainSearch