This is my step-by-step way to create a Masked Rider helmet without spending a fortune. Since I keep a lot of junk, I manage to build a cheap but highly accurate and strong helmet of our favorite bug-eyed hero. This is my first costume so please free to correct any mistakes that I made.
This is the REAL Masked Rider The First (Kamen Rider Ichigo New Generation) helmet:
Kamen Rider The FirstAnd this is my version:
Akizuki's helmetAs you can see, the eyes are and mouthpiece (Crusher) are not yet in place. That could be dealt with later. We have to learn how to make the helmet itself.
DETAIL PICS COMING SOON.
First, you need a mold. Some small cheap plastic helmets can be bought at Toy Kingdom or if you have a bigger head try Ace or True value hardware. I got mine from Ace at 140 pesos.
Now that you have a mold, you must prepare it for the paper-mache. In this case, since the helmet has a visor (tuka), I have to saw the visor away using a hacksaw. A fine hacksaw blade is recommended for thin plastics. After sawing, I just sanded it cleanly.
Removing the visorNow the helmet is completely half-round. Since MR’s helmet is extended up to his nose, we have to extend the helmet downward. I took some window screen from our bodega and cut a piece 1 ½ feet long and four inches wide (depending on the size of the helmet or the size of your face). Attach the screen to the underside of the helmet using masking tape.
Attaching the screen extensionNow that we extend the helmet, we are now ready for the fun stuff: paper mache!. Prepare your materials first, newsprint paper (Buy and Sell is best), pasty adhesive, water and lots of rags. For pasty adhesive, you can use gawgaw or Elmer’s Glue. Mix 50 percent water to 50% Elmer’s.
Since I want this helmet to be made entirely of recycled parts (and I don’t have money that time to buy Elmer’s), I scrounged my dad’s stuff for alternative adhesive. I found a half box of Methylan Wallpaper Paste (from the renovation of CH_Akizuki’s house). The label says mix the whole package of the paste to four liters of water. Since it was only half-full, I used two liters of water. This is critical, mixing too much water will make it malabnaw, and too little water will make it too thick. Mix the powder paste to the water until it all dissolves. You will notice the mixture is becoming thicker by the minute.
Tear the newspaper (do not cut) then set them aside, the smaller the mold the smaller the pieces. Apply petroleum jelly or oil to the mold so the mache would not stick and come out easily. I didn’t do this because I want to make the helmet strong and secure. The plastic helmet would later become a solid part of the costume. Soak the newsprint in the paste and stick it to the mold by layers. One trick is to use thick pieces of newsprint for the first layers then use thinner prints for the finishing layer. To save as much paste as possible so you can use it again, do not soak the paper in the paste. Just spread the paste on the mold using your fingers then apply the paper. Repeat the process until you get the desired results. The paste can be easily washed from your hands using tap water.
Let the paper mache dry thoroughly. If you do this correctly, you will have a nice piece. You can proceed to sand the helmet. Use rough sandpaper (50) to remove big lumps. To get a porcelain finish, start with a medium grit sandpaper (80 or 100) and finish with a very fine grit (300 or 400). It's best to work in stages, progressively using finer and finer grits. Cut the eyes holes using a very sharp hobby knife.

If you are satisfied with the results, you can smoothen the mache using the following methods (Thanks to Poli for this):
1. Wood Glue Filler: You can use Elmer’s or Stickwell. Smother the filler to the helmet and let it dry then repeat the sanding to get a nice finish.
2. Polymer Resin (Masilya): Apply this inch by inch after mixing since the masilya dries so fast. Use wet sandpaper to smoothen the masilya after drying. Wear gas mask since the dust is toxic.
3. Paper clay: Smother over the helmet then use your fingers to smoothen the surface.
4. Elmer’s Glue: Apply the glue on the surface with your fingers, inch by inch, letting the glue to dry before proceeding.
If you’re like me, I want my helmet to be strong so it could last for years (this is my first costume so I want to keep it forever). Therefore, paper mache is not enough for me. Still, I want to recycle so I gain scrounge for things that I can used. We don’t have masilya but I found some Bosny Wall Putty. Using a spatula, I applied the thick cement-like putty to the helmet. That is where my problem starts.
After the putty dried, the helmet resembled the surface of the moon. Worst, some cracks appeared on the putty. To fix the problem, I sanded the dried putty to smooth it out. I attached the small lump in front for the antennas using super glue.

The putty is now rock hard, so I failed to sand the craters off the putty. Therefore, I have no choice but to reapply paper mache atop of the putty. This made the helmet thicker. Four layers to be exact: the plastic mold, the first paper mache, the wall putty, and the second layer of mache. The helmet is now stronger.
After the helmet fully dries, I smother the helmet with Elmer’s Glue. When the glue dries, I spraypainted the helmet using Bosny Tivoli Blue.
Get some small pieces of screen, paint it black, and then install it on the eye holes. Drill two holes on the front of the helmet for the antennas. The antennas themselves are simply solid 14 electrical wires painted silver. Attach it using just Mighty Bond.
And there you have it! The helmet is now complete. Total cost: Just 245 pesos, 140 for the helmet and 105 for the spraypaint.
Next will be the mouthpiece, Henshin Belt, Rider suit, chest armor, boots, gloves and scarf.