Someone want to give me the low down so I can be lazy and not have to do the research myself? I would really appreciate it.

This will be a lot of work for just one piece, not to mention the price for materials. Now are you completely positive it's not on the floor? Check in all the corners, under furniture etc. I find it helps to get down to eye level with the floor, it helps to see anything sticking up, like a teraminx piece.

What materials do I need? Can I go to some shop somewhere and pay for time there, or pay someone to cast it? I have no idea what this requires.

I don't think you can go anywhere to have this done. Also, I don't cast pieces so I don't know everything about it, but basically you're going to need some material, not sure what to actually make the 2 piece mold of the piece. Then you're going to need to buy a 2 part resin material like Oomoo which you will pour into the mold. Again this is a very very rough outline.

This post contains a description of my favorite materials:

viewtopic.php?f=9&t=23954&p=284612#p284600

The most important part is definitely the Sculpey Mold Maker. It compliments Mold Star 15 extremely well.

It's a huge investment to buy all those materials, so really make sure the piece is truly lost first.

this one piece is going to cost you alot! both money and time.
I dont wanna sound discouraging but if you wont take the time to do the research you probably wont ever cast that piece.
plus research is what you want in order to cast a good enough piece. So do your research and come back if you have further questions.

Here is a quick list of what you need:

You will need to buy material for the mold. Silicon rubber and catalyst.
And you will need a 2 part resin. This can actually be bought quite small amounts.
I dont have too much experience with casting, but if you want black then Onyx is the way to go. I have owned a few puzzles cast in Onyx. and that is quite nice and black.
You are also going to need a clay for the mold making process.

you will oncourse need material to build a "box" to make the mold in. Legos work fine but its not everybody who has these laying around

I do have yet another option you can do. And that is if you can measure the piece I might be able to design you a complete copy and you can print one.

That is probably your best bet. If you print it in Transparent Detail from Shapeways (clear yellow material) it might come close to the color of your milk-yellow Teraminx.

If you want to have another go at finding it, try this with a vacuum.
http://www.instructables.com/id/25-Uniq ... t-Objects/

The short answer is that there is no short route to what you seek.

If you really want to cast, your best bet is to read the last four or five years of this forum.

Casting parts went from an obscure practice by just the elite puzzle builders to flowering into a real craft by a good portion of the community. Multiple new techniques were developed and refined that made the older methods look painful.

I don't think anyone who has had any success in casting parts will tell you it is either easy or cheap to get started. I was pretty lucky in that I didn't start until some of the better methods had been developed, and I took the time to read a lot which let me avoid a lot of mistakes. I knew what to buy and generally what to do. With some patience (and perhaps a bit of obsessiveness), I was able to get good results on my first try, but I had plenty of mistakes later.

The patience you put into it is a large determiner of the quality of the result. So if you don't have the patience to do research, don't expect to get a good result.

I would suggest posting on Marketplace. There is a chance someone has a broken Teraminx and might be able to help you with a part (one broken teraminx could supply a lot of spare parts to the whole community...). Another option is to contact one of the sellers (like excalvin, for example) and see if they might have a spare to sell you.

Dave

Did you try to contact MF8 about this? (Assuming its an MF8 Teraminx) I had contacted them with a similar problem and they offered to throw the piece in if I ended up ordering something with it since shipping one piece would not be very logical.

Or how about selling spare parts of your defunct teraminx on eBay, and then using the proceeds to buy a new one (or two)?