is there a clone method for clear plastic fins

I'm talking about the set found in the beta launch vehicle, MX missile, or later Gemini titan. Is anyone making and selling something like that ?

There are several methods. I know that there are TRf'ers that have experience in this. You can do through-the-wall with clear fins. I have done this on my 5" diameter Gemini-Titan. On smaller models this probably still can be done, but I have preferred to use a clear plastic tube around the model and attach the clear plastic fins to it. I have had a problem with getting clear fins to stick with CA to the clear plastic tube. There may be better adhesives out there. I bought a different adhesive, but I have not tried it. Also, it may be difficult to find a clear plastic tube that goes around your model. One time I bought a clear plastic tube, cut it and glued it together again in a way to make a different diameter.

Polycarbonate makes good fins, it's available from Tap Plastics. However, it doesn't bond well with epoxy so you need to use mechanical mounting; see what I did for the Crayon Pack (those fins were acrylic, and one broke on landing).

unfortunately there are no direct replacements for the Twist lok clear fin units you referenced. But there are any number of ways to create your own using Clear tubing and sheet. One warning about Acrylic and modified Acrylics is they do NOT make good materials for flying models. both are way to brittle for our use. Clear Styrene, Polyethylene & Polycarbonate tube & sheets are by far the better choice.
I've been using Clear Polycarbonate on Scale, PMC, & All kinds of Odd-Rocs for many decades without a single fin problem caused by dissimilar material seperates or cracking. Many of my still flying Large Clusted Odd-roc's with Clear Polycarbonate (Lexan) fins have more the 20 flights and as many years on them. By far the majority of these models used "Epoxy Rivet" Direct attachment method. TTW has never been one of my preferred methods though it can be used if the model is going to fly on Larger then G motors.

There is a very extensive Tech-Tip available for download at the www.narhams.org web site in the Library section under tech-tip-017 "Working with Plastics". This Report and photo "How-To" will give you just about all the info you'll need to work with and create your own permanent and removeable fin or fincans for whatever model you happen to be building.
Below are a couple photos from this Tech-tip and a couple of my flying models.
Hope this helps.

Those clear fin units are made of GPPS which may be repaired with MEK. You may substitute a similar unit in black HIPS plastic from another kit.

I make clear fins from the clear plastic of packaging materials and bond it to a balsa wood root with CA gel. Sometimes the clear plastic sheet from some picture and poster frames is a good source.

The black plastic fin unit from the new Estes crayon rockets works on the old Twist Lock rockets. I have an MX Missile and Titan II and confirmed it works. Of course it isn't clear, but if you just need something to allow you to fly it, these new fin units will work.