Kotobukiya Technique Impossible Eva-03 – Part 3: Preparing parts for assembly

In this post I will have a look at what kind of work needs to be done on the styrene plastic, resin, and rubber parts prior to assembly.

Styrene plastic parts:

I start by cutting all parts from the sprues. The parts are free of mold release agent, so washing them prior to assembly is not required. However, as I mentioned in the first part of this build report, the plastic parts have many sinkmarks and other issues. This means only a few parts can actually be assembled at this stage: the parts making up the top of the left shoulder pylon (step 10), the right shoulder pylon halves and knife holder halves (step 11),  and the gun halves (step 19). Aside from the knife holder, these parts need to be held together while the glue dries as they otherwise tend to separate:


Once dry, all of these parts will show some serious seams that will require repeated filling. Just like all of the other styrene parts really:


Yes, the sinkmarks are sometimes so bad that the parts need filling almost everywhere. Once the putty has sufficiently dried, I wet sand the parts a first time, then let everything dry. The parts are then inspected and the filling and wet sanding process gets repeated until I am satisfied with the result. They are then primed using a spray can of black Mr. Surfacer 1500.

An example showing some of the filled areas after sanding:


Resin parts:

Unlike some model builders I usually try to clean up resin parts as much as possible before washing and sanding them, leaving only minimal tab remains to remove.


Some of the resin parts on the Eva-03 seem to have suffered a bit from mold degradation and needed more clean up than I expected. One of the additional long arms had a big chunk of excess resin right next to the peg that will hold it to the upper arm, which (of course) broke off when I tried removing the excess resin. I glued the peg back on after clean up and I will later reinforce it with a piece of metal rod.

After initial clean up, I wash the parts with soap under running tap water and immediately also wet sand them to remove the remains of the molding tabs and molding lines as much as possible. The resin parts are then air dried, given a 1 hour soak in 95% alcohol, and air dried again.

Some parts, especially those of the legs, are not entirely the right shape and don’t fit together well. These parts are made to fit better using the hot water method (immerse in hot water for a while until resin softens, straighten, cool – repeat if needed).


In the case of the lower legs, I only softened the front part of each lower leg and then attached both the front and back parts together by wrapping some masking tape around them:


Any remaining irregularities are filled with Mr. Surfacer 500, left to dry, and wet sanded again. The parts are then inspected and the filling and wet sanding process gets repeated until I am satisfied with the result. They are then primed using a spray can of black Mr. Surfacer 1500.

Rubber parts:


I start by soaking the rubber sleeves in a bowl of water with dishwasher liquid added to it. After several hours, the parts are washed under running tap water and then air dried for a night.


I then cut them into shape according to the instructions in the manual, paying attention to the orientation of the parts (especially important with the knee sleeves! and ) what needs to be cut and what doesn’t. I found that using some small scissors with curved blades, such as certain nail scissors, are perfect for this work. Don’t use a modelling knife; the parts are very soft and it’s easy to make a mistake. The parts have lines molded into them where they need to be cut. However, in the case of the knee sleeves, a part within those lines needs to be cut off (but this can wait until you assemble the legs). The additional pair of rubber sleeves for the arms included with the Eva-03 is used when installing the extra long arms (step 20); only a small part of these sleeves is actually needed:


Due to problems with the assembly of the upper back on my Eva-02 that I want to avoid on the Eva-03 I cut away a little bit more material from the hole that needs to be cut into the upper back sleeve (be careful not to remove too much additional material):


Trimmed parts shown below:



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