I turned Balenes and Boye interchangeables into circular needles, and some skewers and pick up sticks into straights - and you can, too! It's really quite easy.
First, have a look at my article, to get an understanding of how it all goes together.
What I'm doing here is exactly the same thing, only with plastic Balenes instead of wooden dowels. MUCH to my surprise, it's extremely easy to drill into plastic needles - MUCH easier than drilling into wood. First, plastic is so much softer than wood, and it has no grain. When drilling into wood, the drill bit seems to follow the grain of the wood, and sometimes, come out of the side of the needle, as indicated in the article.
Step one - saw off one pointy end of one of the Balene double points.
Next, drill into the end of the needle - just like you did with the wooden ones, but look how much fun it is to drill into plastic! Twirlies!!!
Because I think that these twirlies are just too cute, I'll treat you to another photo, lol. 
Notice a very important point - twirlies means NO sawdust! A very clean activity! (I made my next pair in the house, at the dining room table...)Since it is so easy to do, just drill the whole length of the drill bit.
Here is what you end up with - a deep hole.
Next, shape the shoulders of the "hole" and proceed as in the article with notching the Weed Whacker Filament and gluing it into the hole and wrapping with plumber's tape and knitting.
These needles are wonderful - - Very flexible, very nice. These are a Balene size 3. Oh - wait! I had to reshape the tips - see - 
On top is the original shape, and below it is the reshaped. I just used my Revlon nail file - it only took a few seconds. I really hated the original shape - those little shoulders were annoying. Small changes can make big differences!One point - when I made mine, I used the same glue that I always use - the Locktite Household Adhesive - and it didn't dry! Now that I think about it, it makes perfect sense - plastic weed whacker filament inside of a plastic hole is just the same as sealing it in plastic, right? But, of course, this didn't occur to me at the time, I just thought that I was being my regular old clever self, lol. When did I make this discovery, you ask? When I was on the road, on our trip to Moab, and of *course* I didn't have any other needles. Sigh. So, I just wrapped the plumber's tape onto the join, really really really tightly, and hoped for the best. Since hoping for the best nearly always worked, it worked for me and while it was decidedly weird to knit with needles which are swiveling around on the cables, it all held together and I knitted a perfectly decent pair of mittens and I didn't even cry or anything, lol.
Now that I've successfully made these circs out of plastic dpns, I'm going to do some plastic surgery (get it? get it?) on a batch of circs which my mom gave me. They are her old ones and they are lovely needles with awful cables and awful joins. Besides, they are *all* way too short for magic loop, so I'm going to repair the whole lot of them.
Now, on to an experiment which didn't work out as well as I had hoped. I've used these for many projects, most recently for knitting a darling little alpaca hat for my dh to wear under his bike helmet, and while they... knit... they annoy me. See, I thought I was being all smart and all and I ground down the join end of the needle, but all this did was to provide a place for the smooth finish to chip off and get all pokey and scratchy.
This was a pair of needles which someone, somewhere along the line, gave to me.
They were new in the package - Boye interchangeables - size 2 - no cables, just the needles. So, I chopped off a bit of weed whacker filament, glued it in, and ground down the straight sides to make a smoother join. But, like I said, it isn't completely satisfactory as the finish is now flaking off and poking my yarn and me. Were I to do it again, I'd leave the straight sides as they are, and do a little sculpting with the pipe tape. Also, the pipe tape doesn't adhere very well to the metal, so I'll probably not repeat this experiment. That is, until someone gives me another pair of Boye interchangeables...
See how shallow the hole is? This doesn't inspire confidence. But, I have to say that they've knitted just fine, I'm simply whining.
See how little difference there is between the diameter of the cable and the needle? I should have left well enough alone... You can see little bits of glue in the area of the join. I learned my lesson with the plastic needles, so I used some sort of odd-ball plastic epoxy on these. It worked out just fine.On rare occasions, I like to use straight needles - always short ones.
Here, you see my little collection.From top to bottom, roughly left to right, you can see a pair of needles which I made out of culinary skewers, a pair of Britanny Birch dpns - reassigned (with a lone Balene in between), a pair of pickup sticks - reassigned, and more culinary skewers. Missing are my most faves, a particularly short pair of wooden dowel needles which are loaned out to a friend. I made the skewers and the dowel pairs in order to knit the blue alpaca neckwarmer which is way down below.
The pickup sticks make great needles! Here are two different boxes, one from the dollar store and one from the Goodwill. The box on top are filled with perfect number 2 needles, which I used, once upon a time, to begin my Heere Be Dragone shawl (must get back to it...) and the box on the bottom holds perfect number 3's. No, the Goodwill didn't mark the box, I did, lol.
I tied the stoppers onto the needles with this "yarn" 
and it works perfectly. It's way too cute, too - a nice, bright greenish yellow.
Making needles out of dowels is easy - just do it. You can finish them or not, you decide. The skewers, on the other hand, are a pain in the neck. I ended up soaking them in Formby's oil finish, then letting them dry, then steelwooling them and yes, they came out FANTASTIC, and are wonderful to use, but way too labor intensive for me. I had to do this because the skewers are quite splintery, and unusable in their au naturale form.
Next up - more adventures with needle-felted finishing techniques!