Hello, dear RC hobbyists! In this post I’d like to describe and demonstrate the SIMPLEST way of casting aluminum parts of all complexity levels.
I think all experienced RC automobile hobbyists one day face a problem arising from fragility of stock plastic parts. Replacing them with aluminum parts is a solution. However, this can be quite expensive, so I chose to CAST them myself.

Now, let’s get down to really casting it.
In order to cast a part, you need the following tools:

1. Clear mind and crafty hands
2. A melting pot
3. A pile of scrap metal. I strongly recommend that you use DURALUMIN, because pure aluminum won't cast well
4. A mold
5. Blowtorch
6. Ten or more bricks

Step 1
To make a melting pot, take a piece of metal pipe and weld a bottom to it. Duralumin melts at 650°C, so use steel pieces. For better convenience, I recommend that you make a nozzle at the top.

Step 2

Now the most exciting part of it – casting a MOLD. Based on the complexity of the part, you may need either a one-piece mold or a complex one. My mold consisted of two halves. First, you should make your part maximally simple (scotch-tape all holes), to remove all obstacles from the molten duralumin’s path. Use plaster (not the Plaster of Paris!). The best option is the kind of plaster than is used in sculpturing.

Grease your mold before pouring in plaster, so that it won’t stick to the surface (use oil, waste oil, lithium grease, etc.); grease the template as well.

You must be very careful while pouring in plaster; and shake the mold a little to remove bubbles (some users even apply vibration tables).
NOTE: plaster hardens very fast, so don’t be too slow to put the template into the plaster mold.
Well, I all but missed that it is imperative that you put in a rod or a stick into the mold before pouring in plaster to make an inlet for duralumin.

When the first layer hardens, prepare it for further casting. Drill four shallow holes (to hold the halves together while casting), grease the upper half and pour another layer onto the first one.

When it hardens, take it out of the container and separate the halves.

Remove prominences using a piece of sandpaper or a knife and make a few shallow (2-3mm deep) cuts in one of the halves with a metal saw.

NOTE: These cuts will serve as outlets for gases to prevent the molten metal from bubbling during the casting process. It is ABSOLUTELY MANDATORY that you dry both halves. The better you dry it, the better the quality of the part you will get. You can use all types of heat sources to dry it (including ovens).
Before casting, line the inside of the mold with soot to prevent the liquid metal from sticking to it.

Step 3
Build a makeshift furnace using the bricks (a blowtorch won’t melt duralumin) and put a metal plate on top of it. Now let’s really cast it!

Remove dross from the surface of the molten metal from time to time.
Pour the molten duralumin into the mold and wait until it cools off.

Polish the newly cast workpiece, cut off unneeded prominences and drill as many holes as you need.

Now, that’s it. Dig it, try it and remember that there is no business you cannot do!

This is the translated version. You can read the original Russian article here.