Mold making question

You are Lucky Dave;

  Since I moved to the " Lone Star State" almost thirty years ago I haven't been able to find a store that even holds a candle to TAP. These folks here seem to know less than I do when I learned from the TAP guys in Concord Ca. When I went in to buy scrap for my projects!

    And they are supposed to be proffessionals? They didn't even know what High U.V. Exposure, Non Glare Cast Sheet was! Lexan and What everyone calls Plexi is either cast or rolled like metal in it's soft forming stage. So for most of my projects I buy Storm Door Plexi Panels! From Home Depot!

Here is a link that shows a pretty simple/inexpensive way to make replacement parts. 

https://forum.ipmsusa3.org/topic/20356-110th-figure-start/

The piece is for a figure, but should work of any parts. Good luck.

Tanker-Builder

Now;

     Here's a simple answer to your question. Take plastic sheet of the approximate base thickness. Cut larger than needed. Then carefully copy the other one. It shouldn't be that hard. You will probably need to laminate some some pieces together.

 

 

While it is possible to get pretty thick plastic sheet, there is an advantage to laminating two sheets of half the needed thickness.  This leaves a perciptable centerline which eases shaping the airfoil.

I use casting supplies from a Tap Plastic Store in my area.

I use silicone rubbers of different kinds, and a 2-part casting resin I really like.

The fact that your here asking these questions tells me your in-experienced with any kind of reproduction work, so I like the last answer about using balsa wood, if you have any skills with carving.

Tough trying to help you not knowing your skills and skill level.

I'd probably cut it out of basswood and sand the profile, seal and paint.

Now;

     Here's a simple answer to your question. Take plastic sheet of the approximate base thickness. Cut larger than needed. Then carefully copy the other one. It shouldn't be that hard. You will probably need to laminate some some pieces together.

    Here is a interesting tip. Have you seen those Pin toys that you can make a copy if your hand or whatever? If you have one around, then Take the undamaged fin and fuselage rear and make a copy in the pins. Kinda like a contour guage. Then drop the new in every once in a while. You'll be able to tell if the shape is right!

Yes it is possible.  However, a simpler fix might be to trace the good part onto a sheet of styrene of appropriate thickness and file or sand it to the contour.

Can you post a photo of the damage?  We might be able to suggest a fix versus making a new fin.