Most lumber yards sell medal stair risers from 3 to 8 step, I bolted on two P/T 2x6's and cap'd them with my composite decking, Rona sold special composite screws that flush mount, worked great. I ripped the front caps on my table saw & miter cut to hide the boards, a bit of work but a nice finish.
If it's just the 3-4" strip, you need to rip a board on a table saw, easy fix.
D.
Home Depot Stair Risers ....
https://www.homedepot.ca/product/pyl...ack/1001312356
.
.
[IMG]
[/IMG]