Here's a popular ergonomic design. This project is easy to do and can be done with in one hour of work. Also this can be done with small piece of scrap.
$30 - $50
|Board||1 x 2, 5"||1|
|Common Nail||2 1/2" or 3"||1|
|Leather Strip||1/8" x 8"||1|
|Stain of Choice||Nil||1|
|Finish of Choice||Nil||1|
1 Cable Drill
1 Scroll Saw
1 Tape Measure
Handle - 7/8" x 1 3/8" x 5"
Step 1: Choose the Wood
In this project you can use new or scrap hardwood board that is at least 3/4" thick, 1 1/2" wide, and 5" long.
Step 2: Design and Cut
Trace or draw out your design into the wood. Using the bottom right corner of your piece, make sure you leave straight edges at least 1 1/8" long up and also to the left of your bottom right corner. You need those two flat surface for the nail and bottle cap. Make sure to leave enough space for large nail that will be inserted. You can try out the handle design first to see what fits for your grip. Once you find the perfect grip design you can start to cut it out with a scroll saw or band saw.
Step 3: Mark the Nail Path
Now you need to mark the handle at 90°. Mark a line down the center where the nail will be placed. Mark the front end as well when you find your center line.
Step 4: Punch the Nail Hole
After you mark the center line of the handle, now you will punch a hole in the line that intersects. Use a drill bit and a clamp when punching the hole.
Step 5: Drill the Rear Hole
Before drilling out the nail hole, use a 5/32" bit to drill a hole in the rear for your leather strip, paracord, string, etc.
Step 6: Choose a Nail
Here you need to choose the nail from 2 1/2" to 3" long. Also, try to find a nail with a head that has a sharp 90° corner where it meets the shank. Many nails will have a curved transition between the two but a nail with sharp corner works much better.
Step 7: Find the Nail Diameter
Test out different bits on a piece of scrap wood to see how your nail fits. The hole should be loose enough to pry the nail out after pushing it in, but snug enough to where it will take a little effort to get it back out.
Step 8: Drill the Nail Hole
Now secure the handle with a clamp or vice grip. With the center line facing towards you. Drill down the center 90° from the face. Make sure you will not over drill just enough with the length of the nail to be inserted.
Step 9: Sand and Finish the Handle
Sand the edges until you can grip the handle comfortably. Once done apply finish before inserting the nail.
Step 10: Mark the Nail
Bending the nail correctly might take some trial and error before getting it right. Do a mock-up with your handle, nail, and bottle. Once you get the head of the nail under the bottle cap, mark the nail at the top half of the hole. See picture for reference.
Step 11: Bend Nails
Using a vice or clamp place the mark spot to the edge and hammer it over at a 90° angle.
Step 12: Test It
Insert your bent nail into the handle's nail hole. Push it all the way in and try to open a bottle with your opener. If it doesn't work well, pry it out in a twisting motion with pliers. Get another nail, make adjustments, and try again.
Step 13: Finish the Job
If your nail is still in the handle, twist it out with pliers. Insert some super glue into your nail hole and hammer your bent nail back in there. After that, tie your leather strip, paracord, etc. through the rear hole and you are finished.