The Needle Case is available with or without a built in Threader. The cap of the case is made with a tapered tenon that matches the taper of the mortise in the Case. Just push in to replace the cap, or pull with a twist to take it off. If a Threader is included it has a smaller tapered tenon that fits in the tapered mortise of the Cap. The Threader is made with 0.005" music wire.
The Cap has a 1/4" rare earth magnet recessed in the tenon so you don't have to tilt it upside down to get needles out. Just give it a light shake before removing the cap and the needles will come out along with the cap. Grab them with your fingers and then pull the cap away. You can have the Needle Case or Needle Case with Threader without the magnet if you prefer.
The Needle Case is a little over 4" long with cap and about 5/8" diameter. The Needle Case with Threader is also about 5/8" diameter and is a little over 5" long with both caps.
These can be made of any solid wood or laminated wood I have available. It won't work with Corian. See Laminates for pictures of laminated woods that are available. See To Order for ordering information. Or just send me an email at David@DavidReedSmith.com