Unless you get overly enthusiastic with 'Black tailllight paint' as I did once;
couldn't find a set of new or used lenses so I hacked in 21W / 55W bulbs
for rear / brake|turn indicators instead. Young and foolish...

Also, now most cars have a third brake light mounted centrally at the
lower or upper edge of the rear window. In queues/heavy traffic this can
often be seen through a couple of cars ahead, giving better forewarning and
preventing pile-ups...

/Michael