So I've seen a lot of people attempting to use regular bondo on their stuff and I've been guilty of it too in the past. However by using a mix of bondo and resin, you can save yourself a lot of work and have beautiful results.

This technique was pioneered by Spase who originally used it with metal glaze, but the same principle still applies to using it with the mix.

The mix is referred to by a few different names and has been used by many of experienced molded armorers like Sean and Link. Usually rondo or mud is the commonly used term.


<span style="font-size:14pt;line-height:100%">Step 1: What you will need</span>

To use this technique you will need

1. Plastic Spreaders
2. 3M painters tape
3. Polyurethane fiberglassing resin (Resin)
4. Automotive styrene based auto body filler (Bondo)
5. Liquid Catalyst (Hardener)
6. Mixing container
7. Respirator (you know the safety rules, please don&#39;t ask if you need one)
8. A fiberglassed piece of pepakura armor
9. Sanding equipment (preferably a dremel and mouse sander)

pic of the essentials to make and apply the mud




<span style="font-size:14pt;line-height:100%">Step 2: Building the tape wall </span>

The piece of pepakura must be smoothed in sections. First you must determine which areas are similar enough that you want to attempt to include them all in a single smoothed surface.

Next take a strip of painter&#39;s tape approximately as long as one of the sides of the section you&#39;ve chosen.




Then fold one edge of the tape approximately 1/2 inch on top of itself. This is critical to reinforce the edge as well as to have the maximum height that the mud can reach before spilling over.




Apply the tape to the section you want to smooth while keeping only the doubled up edge above the surface. Repeat until you have completely surrounded the section. Flare the edges slightly and reinforce adjoining edges so they don&#39;t interfere or fall apart when you are pouring the mud into it.

* NOTE: If you are working with a highly curved surface, make sure the lower points have slightly higher walls to prevent excess overflow.

Before


After



<span style="font-size:14pt;line-height:100%">Step 3: The recipe for mud</span>

Mud is usually made in a 1:1 ratio of bondo to resin.

However, what you want to do is create a consistency that is like mud (very thick but still pours evenly) adjust your mix accordingly to attain that result. Use more bondo to make it thicker or more resin to make it thinner until you have achieved the desired texture.

To mix it, it is recommended to use a plastic spreader cut to a managable size (about 2 inches across).

After the mud is made, use double the recommended amount of liquid Hardener. This allows you to skip having to deal with using two different catalyst materials.


<span style="font-size:14pt;line-height:100%">Step 4: Pour it, leave it, come back later</span>

Make sure the section you want covered is in the most horizontal position it can be before this step.

After the mud is mixed with the catalyst, pour it into the tape walled section. Make sure everything is covered. Don&#39;t overfill it as it will just be more sanding work later.

Wait about an hour and a half for it to set then come back and remove the tape and little excess overspill bits while the mud is still a little flexible before it completely cures.







<span style="font-size:14pt;line-height:100%">Step 5: Sanding</span>

Sand it down to your likeing before beginning the next step.


<span style="font-size:14pt;line-height:100%">Step 6: Do it again</span>

Rinse and Repeat until the whole thing is done.