Metal T-top End Caps (first attempt)

[TopNotch]

For some time, I have wanted to attempt making metal t-top end caps for my yellow car. Why do this? Well, below is a picture of one of my original end caps.

That big hole shouldn't be there. The original smaller hole for the t-top latching rod broke (a common problem), so the original owner hogged it out, and put a rubber grommet in the t-top frame to give the rod a place to go. Not the ideal solution.

Below is my first metal t-top end cap (on the bottom), and what I used to make the mold for it from.

The black end cap is part of a set I obtained from this website, for a whopping $180 bucks. And that's for reproductions, not originals. If I had wanted original end caps, I could have obtained a set from here for a mere $600!

To make the metal end cap, I had to make a mold for it. I read up on this, and made an adjustable mold box like this:

I lined the bottom of  the mold box with modeling clay, and filled the inside of the plastic "original" with the clay. Then I pored silicone rubber mold making compound into the box. When it had hardened, I turned it over, took off the clay, and pored more compound in to make the other half of the mold. Sounds easy, but it wasn't.

Here's the result on my car.

It's not pretty, but it works. I'm going to try to improve my mold, to make it prettier. And then sell these things, because if folks are willing to pay $180 for plastic ones that can break just like the originals, they might pay more for metal ones.
The only problem with the metal end cap is that there is no "give" to it. In the world of imperfect aftermarket car mods, a little "give" is good here and there. To get my end cap in place, I had to use longer than normal screws to pull it into place, and then put in the original screws.

[GTRS Fiero]

When you get the metal cleaned up, powder-coat it the right color.  I know the original was grey, but black would look so much better.

[GTRS Fiero]

I must've missed the part about how this is metal.  When did the metal get into the mold?  What type of metal is it?

Since it's metal, I'd forego the texture, and make the piece smooth.  Not polished, just smooth.

I have noticed that people with convertibles seem to like to rest their hand in that area.  If the metal piece is sitting in the sun, this could be unpleasantly warm.

[TopNotch]

What type of metal is it?

It's a low temperature casting alloy made of bismuth and tin. Harder than pure tin, and I have no idea what pure bismuth is like.

I have noticed that people with convertibles seem to like to rest their hand in that area.

They must not drive the Dragon.

[GTRS Fiero]

No.  Usually on highway cruises.  It's a habit.  Some people who drive vans hold the bars for the mirrors.

[Fierofool]

You might be able to use a wire brush in a drill to take away some of the texture. 

[TopNotch]

Update: I ordered a different kind of mold making compound, and another HDPE board to make a better mold box from. I should have another update in about a week.

[GTRS Fiero]

This project it off to a gread start.  I'm wondering how hard it would be to make these from aluminum, or something with a bit of give.

[GTRS Fiero]

Did you make any further progress on this?

[TopNotch]

I've more-or-less dropped it for now. If I figure out a better mold material, I may try again. The mold material I use is actually supposed to be subjected to a vacuum before it's poured, to remove any dissolved air. If that is not done, the air come out when the hot metal touches it, and that's what causes the rough surface of the molded item. I don't know how much the vacuum pumps cost, but they're probably not cheap.
Edit: Come to think of it, I could probably use my AC vacuum pump, but I'd have to build a vacuum chamber to put the stuff in.

[GTRS Fiero]

The pump itself probably is not the problem.  Probably $50 or so, at a guess.  You still need a sealed container.