Another alternative is to purchase "balsa wood" or hardwood boards at the hardware, hobby or craft store in a comparable size (but it will be a little more expensive).
Building the Spice Drawer Inserts
Okay, so now it gets really easy.
Just glue and nail the 1/4" plywood pieces to the 1x2.
Do this to all of the inserts. I used 3/4" long finish nails.
TIP: Use a 1x2 scrap to hold the other end of the plywood piece up as you nail.
Each insert will look like this.
Installing Inserts In Drawer
Now just set the inserts in the drawer.
You can add a 1x2 spacer at the back if there is extra room.
You can also nail the inserts to each other. Just place all the inserts in the drawer, overlapping as desired to fit your spices. Trace each overlap with a pencil on the front. Then remove and nail together on the back side, nailing through the 1/4" plywood on the back side into the underside of the 1x2.
Best part - using up scraps from various projects, this custom wood insert was FREE!!! And even if you bought new materials, we are talking like under $5 to make this!