How to customize a Casio F-91W: faceplates, negative displays and straps

The Casio F-91W is one of the easiest watches in the world to customize. The case is simple, the parts are small and cheap, and the module inside is the same on every version. That is why there is a whole scene built around modding it.

This guide covers what you can actually change, how each mod works, what it costs with us, and what you give up. If you want to see a combination before you commit, try it in our 3D watch builder first.

What you can change on an F-91W

Most custom F-91W builds come down to four parts:

Part	What changes	Difficulty
Faceplate	Colour of the face, colour of the print, or no print at all	Medium: the case has to be opened
Display	Tinted film, or a negative (dark) display	Hard: the LCD film is delicate
Strap	Resin, leather or nylon	Easy: two spring bars
Your own artwork	A photo or design printed on the face or display	Medium to hard

Everything below keeps the genuine Casio case and module 593. The timekeeping, alarm, stopwatch and battery life stay exactly the same.

Faceplate and print

The faceplate is the coloured panel around the display. On a stock F-91W it is black with a blue frame and gold lettering. On a WC or WB model it matches the case colour.

A faceplate mod replaces that panel or reprints it. The common options:

• A new face colour. Navy, cream, olive and matte black are popular because they sit well with almost any case colour.
• A new print colour. Gold or white lettering on a dark face looks dressier. Black print on a light face looks cleaner.
• No print. Removing the CASIO, ALARM CHRONOGRAPH and WATER RESIST lettering gives a minimal, almost architectural face.
• Classic or minimal layout. The classic print has the frame line around the display. The minimal print, used on the F-91WB series, drops the frame and puts small labels on the sides.

In our builder a faceplate change is ₹999 on top of the base watch, whatever combination of colour, print and layout you pick.

Negative and tinted displays

This is the mod people notice first. A normal F-91W display shows dark digits on a light grey-green background. A negative display flips that: light digits on a dark background.

It works by changing the polarizing film on top of the LCD. The liquid crystal itself is not touched, so the watch keeps every function. The trade-off is readability. A negative display looks striking indoors, but it is harder to read in bright sunlight and at an angle. If you read your watch outdoors a lot, keep that in mind.

A softer option is a tinted film: the digits stay dark, but the background turns ice blue, mint, amber or rose. It is easier to read than a negative display and still looks different from stock.

With us a tinted film is ₹499 and a negative display is ₹1,499. We also offer negative displays with a blue or red tint.

Straps: resin, leather or nylon

The strap is the simplest change, and you can do it yourself. The F-91W uses an 18 mm strap held by two spring bars.

• Resin is the original. It is light, waterproof and comfortable in heat. It is also the strap that eventually cracks after years of wear, so a replacement is never a bad idea.
• Leather makes the watch look older and more considered. Tan and cognac look great with black faces. Leather does not like water, so take it off before swimming or washing up.
• Nylon is tough, breathable and dries fast. Olive, navy and grey are the classic choices. It is the best option if you want a different look without worrying about sweat or rain.

Add a leather strap for ₹899 or nylon for ₹599 in the builder.

Print your own photo

You can also put your own artwork on the watch. On the faceplate, the display window covers the middle, so the edges of your photo show around the display. Patterns, textures and bold colours work best. Faces and text usually get cut off.

On the display, your photo sits under the digits. Simple, high-contrast images keep the time readable. Busy photos make the digits hard to see.

In the builder you can upload a photo, crop it to the exact shape of the face or display, and see it on the watch in 3D before you send it. A faceplate photo print is ₹1,499 and a display photo print is ₹1,299.

What you give up when you customize

Customizing is worth it, but be honest with yourself about the trade-offs:

• Water resistance. A stock F-91W is only splash resistant to begin with. Any mod that opens the case means you should treat the finished watch as splash resistant at best. See our water resistance guide for what that means day to day.
• Casio’s warranty. A modified watch is no longer the watch Casio sold. That is why we list customized pieces separately from our genuine Originals.
• Readability. Negative displays and photo prints look great but are harder to read than the stock display.

The battery is the same CR2016 as before. Changing it works the same way on a customized watch.

DIY or have it built

Straps are an easy DIY job with a spring bar tool. Faceplates and displays are a different story. The LCD film tears easily, the contacts are tiny, and getting dust under the glass is very common. If you have never opened a watch before, a cheap practice watch is a good idea before you open one you care about.

If you would rather skip that, use the builder. Pick any of our genuine Casio colourways as the base, change the faceplate, display and strap, and press Request this build. We check the parts, confirm the final price by email, and nothing is charged until you approve.

Prefer something ready to wear? Our customized collection has finished pieces ready to order.

Frequently asked questions

Can every F-91W be customized? Yes. The F-91W, F-91WB, F-91WC and F-91WG all share the same case and module 593, so the same mods work on all of them.

Does a negative display drain the battery faster? No. The display draws the same tiny current. The battery lasts as long as on a stock watch.

Will a standard 18 mm strap fit? Yes. Most 18 mm resin, leather and nylon straps with spring bars fit the F-91W.

Can I undo a mod later? A strap change is fully reversible. Faceplate and display mods replace parts, so going back to stock means fitting original parts again.