This is my instructable for my very first casting project. Not only is this my first casting project, it's the first 3D model for a prop that I have made end to end in Fusion360 and I'm really please with the results
In this instructable, I will outline the steps that I took to make this prop from Metroid.
Steps covered are: -
- Making the Master
- Making the Mould
Step 1: Making the Master
Before you can cast, you need a master of the thing you want to copy.
You may already have a master ready to go, or you may need to make your master from scratch. All you need to remember is that when you have finished the preparation work, the master must be as close to the quality you want each copy to be.
Remember, any imperfections in the master, will be replicated in the mould. The more time you invest in getting this stage as close to perfect, the more time you save in the finishing stage.
There are many methods to make a master, but in my case I opted for CAD and 3D printing.
I found some reference images online and brought them into Fusion as canvases, starting with a sketch of the side view, and using various operations to complete each part of the model (10 pieces in total).
Although the 3D printer did a great job of replicating the detail of the model, layer lines were still present (and there will always be with FDM 3D printing), so I went through several rounds of priming, and sanding with higher grades of papers until I reached the finish I was looking for.
Step 2: Making the Mould
As this was my first attempt at moulding, I decided to purchase premium quality moulding materials, as I wanted to know that any failures were due to my lack of experience, rather than a poor quality material (remove as many variables as you can).
I opted for Smooth-on products as they are well renowned in the prop making industry. The silicone is measured out by weight and a catalyst added to cure it over time. I used Mould Max 25 for this project.
The first set of moulds I made, I used LEGO form the boxes, however I later discovered that this was a poor choice as the silicone leaked in between the bricks. This was not a major disaster, but I did use more silicone than I needed to. After this initial mistake, I chose to use foam core and hot glue to make the boxes with great successes.
The most challenging part of the mould making process was the 2 part mould for the main body. The first half was placed on a foam core square that was large enough the body did not overhang. Next modelling clay was placed around the master so that only half of the model was exposed. The clay was trimmed to square it off and foam core sides were cut and hot glued in place. A large hex bolt was then used to created registration marks for the 2nd half of the mould that would be used to lock into place, time after time, cast after cast.
The Silicone was mixed and poured over the master and allowed to set for 1 day. The sides of the box were then removed and the silicone + master were flipped over and the clay removed, taking care to remove all the clay. The sides of the box were then hot glued back in place. This is where I made my 2nd mistake. Make sure you use plenty of mould release on a 2 or more part mould! As silicone only sticks to silicone, a good layer of mould release is needed to ensure the two halves of the mould will come apart later on.
With all the parts being moulded, the only thing left to do is wait 24 hrs.
After the Silicone had fully cured, it was time to remove the master parts. The main body was problematic due to insufficient mould release and the top edge would not come apart. I decided to leave this as it was is i didn't want to tear the mould. The other parts either popped right out, or needed a registration cut (ZIG ZAG seam cut) to allow the part to be liberated from all that silicone goodness.
Step 3: Casting
Time for casting: -
As with moulding, I decided to go with premium products to reduce the variables and leave just my lack of experience as the main reason for any failures.
To give me more time to work with the material I opted for Smooth-cast 310, which I hoped with the longer cure time would also be a little bit gentler on the mould.
The process is very similar to moulding with mixing quantities of part A and part B according to the volume of the mould and mixing instructions. Adding a black colour to the mixture gave the final cast a nice grey colour, but I was a little heavy handed with the grip. This mixture was then poured into each mould in turn until all were full.
For the 2 part mould or moulds that needed a relief cut, I used paces of foam core and elastic bands to hold the parts together. This worked well for the most part, with the exception of the 2 part mould. this did leak a little and on future pours, I will cut some thin plywood and secure with bolts and wingnuts to secure and seal the parts together.
Step 4: Finishing
Once the parts had been de-moulded, it was time to start final finishing and assembly.
I started by attaching the grip to the main body, and masking off areas where parts would be fitted and paint was not needed.
This was given an initial primer coat and a base coat of black.and then a metallic silver base coat. I applied mustard in areas where I though the blaster would receive wear and then applied a black top coat. once dried, I brushed over the areas where the mustard had been applied to reveal the metallic under coat giving it a weathered look. Each individual part had a similar process (Black base coat > Metallic top coat) paint treatment until it was time to paint the muzzle, which I decided to attempt bluing (Thermal discolouration of metal).
I did this by hand with a brush starting with a gold paint and blended with washes to a final blue colour to simulate heat distortion. Each part was then assembled using CA glue.
The finishing touches were to give it a dirty wash of acrylic black and brown paints all over, before being wiped off. I did a few passes of this until I was happy with the finish.
All in all I am super please with this first attempt and the results speak for themselves.