Get the wood cut the wood to the correct size and sanded if need be.
Drill 2 x 7.5mm holes at either end as show in fig 1.
Drill 2 x 5 mm holes near those.
Countersink the larger holes to about half way, so that you can attach the nut of the 4mm terminals.
Insert the 4mm terminals in the larger holes, one of each colour in either end, and secure with nut.
Attach the plastic cell holder with the 2 screws (diagonally opposite), first drilling holes, and making sure that the end with the spring goes near the black terminal.
Cut a 5cm piece of each wire, strip the ends and solder onto the tags on the plastic cell holder, making sure you do not take to long or the tags will melt off. Ensure you have got red wire to the red terminal and black wire going to the black terminal. Then push the wire through the 5mm hole and out the other side so you can then solder it onto the 4mm terminal.
It should look something like fig 2. these are usually very durable and can be used in conjuction with bulb holders etc.