In the 1950s, Esterbrook made ballpoint pens that matched their J series fountain pens and pencils. The ballpoints were the FJ and the Wordathon. Those pens used a very unusual proprietary refill that has not been made for many years and no currently available refill works in these pens, leaving them useless.
To address this problem, an adapter has been created using 3D modeling and printing. The adapter accepts a standard D1 (mini) refill which is readily available at most office supply outlets. It has proven to be very popular and now more than one hundred of the Esterbrook ballpoints have been brought back to life.
The adapter is a print to order item at Shapeways. You can place your order for one or many adapters there and Shapeways will print them and mail them to you. The entire process takes less than two weeks, including shipping time. You then add the D1 refill and your Esterbrook is ready to write.
My favorite D1 refill is the Uni Jetstream SXR-200-07, 0.7mm, or SXR-200-05, 0.5mm, which is available online from Jetpens.com or from several sellers on eBay. The Montverde and Schmidt refills are very good and usually available at local office supply stores.
To visit my store on Shapeways, click this link: Esterbrook Adapter
If you have a question about the adapter, please email me: BamaPen@jehubbard.com
Here are some pictures of my Esterbrook FJ with its original refill and the adapter. Click on either image to open the gallery for larger views: