These like most of the bits can be bought made of alloy, but as mentioned before this is a DIY not to large budget project, so buying in stuff is out. While alloy does look really nice, most people will be looking more at the actual R2 or in my case R6 unit, than what its made out of. There are some good alloy coloured paints around now, one being if you can still get it Humbrol aluminium metal coat. This was one of there paints that can be polished to look like real alloy, (well nearly anyway,)
One thing to remember when painting stuff especially if itís to look like metal, try if you can to use an airbrush. Even a cheap one will give better results than a can. In the UK, you can buy a cheap Revell one from most model shops or even Halfords sell it I noticed while in there the other day, and cans of compressed air to power it.
Apply the paint in several very thin layers. If you use a can, it applies far to much at once, building up, and leaving very sight marks on the surface. This is amplified if spraying silver or gold, but using an airbrush and several thing coats avoids the dimpled effect, and if far harder to tell apart.
So as these need slots machining into them, I made two slabs of polyurethane resin to make them out of. Very simple method using the pasta making roller thingy, roll some sculpy out to the thickest setting, then cut into thin strips and construct a box on a sheet of glass a bit bigger than you need. Then spray the whole area with spray wax polish and fill with fast set resin and wait five minutes.
When set remove the sculpy and with a wallpaper scraper gentle poke it underneath and if waxed right will just come off. Then stick the template on, using Pritt Stick, (as mentioned before, this is water soluble so comes off with no mark.) and youíre ready to go.
I donít have any CNC stuff so by hand it is done. Personally I feel there are to many people with a computer and CNC router these days, that make stuff then people are like wow, did you make that. Anyone with half a brain can create an image in 3D on a computer and let a machine make it, but it takes real skill and practice to be able to make it by hand. For me the actual creating the part from scratch is the thrill as its my own work, not a computerised machine.
With the main slots cut, there is just left the task of squaring off the corners by hand. This is done with a simple but sharp wood chisel. The resin is not hard enough to warrant a hammer, so with a bit of body weight pressed down the chisel cuts through.
Next is a backing. This is a sheet of 1mm plastic glued on the back with two part epoxy glue. It is however smaller than the front, as a recess is needed all the way round for fitting against the body.
Last off is the finished painted item in pressure cast resin. I use Smooth-on 30 minute cure resin for these, as this gives enough time to thoroughly mix the resin, (I use a electric whisk), then de-gas it, (gets rid of 99 percent of the air,) then pour it in the mould and place it in the pressure pot and slowly bring it up to 60psi. Any resin that cures quicker than this would mean the possibility of having to rush it, and thatís when mistakes happen.