As befitting a large, high-end kit, the Rick-Dom HY2M has under-gate treatment on its parts~!
Even when you pull them off the runners, gate marks barely remain.....but there are some odd things going on. -.-

For example, stuff like this... even on the same part, some obviously visible outer surfaces get the under-gate treatment
while others just have the gate stuck on the side leaving marks.. -_-;;;;;;;
In short, the under-gating is pretty inconsistent. If you're gonna do it, do it properly...

On top of that, there are plenty of spots where they unnecessarily applied under-gate treatment to areas that are hidden inside and can't be seen anyway.
And on the flip side, there are lots of exterior parts where the under-gating is only half done..
It's all over the place, but I guess it's still better than having none at all. Hmm.

First off, this kit uses a lot of hex socket screws like the ones shown above.
Obviously, there's no way to tighten these with a regular Phillips or flathead screwdriver.

So you'll need a hex key (Allen wrench) like the one shown on the upper right.
But this kit doesn't include one.. so you'll have to track one down yourself.
It's not something most people have lying around, so you'll probably need to buy one — but you can easily find a set with various sizes at a hardware store or large home goods store.
Since this kit uses two different sizes of hex screws, you'll need two different hex keys.

The hex screws tighten into nuts like those shown — there are two types included: a standard locking nut (left) and
a nylon insert nut (right) for adjusting the stiffness of moving joints.

All the wires come pre-stripped at the ends like this, which is a really thoughtful touch.
My job is as an engineer developing wireless communications equipment, so I spend a ton of time twisting wires at work..(-.-;;)
When you strip the insulation back a little and leave it like that, it's much easier to grip the rubber part and twist the wire.
You really do need to twist the metal strands together, otherwise they splay out and become a pain to connect — so it's a nice bit of consideration on their part.

The left one shows what happens when you just pull the insulation off without twisting — the strands go everywhere and it's a nightmare to connect.
If you grip the slightly stripped insulation at the tip and pull while twisting, you get a nice, neat twist like the one on the right.
That way you can properly insert and wrap the wire around the metal terminals.
(To be honest, getting a perfect twist like that does take a bit of practice.. -.-v)

The mono-eye lights up with a red LED, and you even need to connect a resistor to regulate the voltage.
The method is to first wrap the wire around a yellow metal ring, then insert the LED or resistor's metal legs into the ring
and crimp it flat with pliers to secure everything.

The mono-eye LED mounted in the head. The wire is routed out through the bottom of the head and connected to the power supply in the torso.

There are no LEDs in the arms at all. There's no real inner frame to speak of, just a basic skeleton.

With just the skeleton, the arms bend really well.

The inside of the shoulder armor has a separate red part...

Three LEDs operate in the sole of the foot.. the positive and negative terminals of each LED are connected using metal plates and screws.
Since it's tricky to hold the metal plates in place before tightening the screws, it helps to tape them down beforehand.

The wires are routed out through the back of the foot and run upward from there..

Three more LEDs are also installed in the verniers at the back of the foot.

The wires from all six LEDs — in the verniers and the sole — run up through the leg and connect together..

threading through the gaps between each joint and coming out at the top of the leg.

The inside of the leg armor also has a separate red part..

The waist uses a double ball joint, and you adjust the stiffness by tightening or loosening the screws and nuts with a hex key.

The verniers on the rear end also have three LEDs operating, same as the back of the legs..

All the wires need to come together at the top of the torso.

A shot mid-assembly. Those two comb-like pieces — one is the positive terminal and the other is the negative.
Since red is + and black is -, connecting them to their respective combs completes the power supply section.

The structure of the backpack vernier section.

The power connection diagram inside the backpack verniers.

The cockpit interior also lights up with an LED, configured as shown above.

The round section on the chest also has an LED that lights up.

After putting all the armor on. The upper torso is designed to open and close.
To replace the batteries or operate the switches later on, you just pull the upper torso section out slightly and lift it off to make adjustments.

The structure of the upper torso power section. There are 3 switches for controlling the head, cockpit + chest area, and the remaining verniers.
The black wires (-) all connect to the left comb terminal, and the red wires (+) all connect to the right comb terminal.

The entire body runs on batteries of this oddly specific size as shown.
They're manganese batteries called N-size or NS-5 cells — same diameter as a standard battery but 2/3 the length.
You can find them at electronics specialty stores or large stationery shops.
Prices range from about 700 to 2,500 won for a pair depending on the store ^^;

A special component is used for the bazooka switch.
It works on a principle called the Hall Effect — the left piece is a magnet, and the right one is what's called a Hall IC.
The way it works is that when a magnetic field is generated near the Hall IC, the IC allows current to flow through.
Simply put, instead of a click-type switch, the LED lights up depending on whether or not a magnet is brought close to it.
(This is one of the methods the HY2M series loves to use.)

First, a red LED is installed in the lens section of the bazooka..

And a Hall IC is connected between this LED and the power supply.

Then a magnet is positioned inside the hand.
As you'll see in the finished photos, when this hand is brought close to a specific spot on the bazooka, the bazooka lens lights up.

The Rick-Dom HY2M comes with some flashy stickers.
However, they aren't pre-cut, so you have to cut each one out individually before applying them.