For a field engineer, quick approximate measurement of sizes of things is handy. Carrying a meter is carrying of additional piece of equipment. There are cellphone apps that show a measuring scale on display, however this is limited by the size of the display and in field use increases risk of scratching the display.
A scale was manually etched into the side of the phone's casing, using an electric handheld Dremel-type mill. Its length is 100 mm. The 0 position has 10 mm offset from the base of the phone, allowing easy manual addition when using the phone base as a reference.
Some phones have possibility to attach a wrist strap or a neck strap, so they can not be so easily dropped during operation and/or can be carried on one's neck. Nokia E61 omits this feature. Ask them why.
A soldering eye of suitable size was bent, and after careful surface preparation (sandwheeling the surface of the eye, sandwheeling the protective plastic-like coating from the phone's casing at the joint place) it was glued to the phone casing using a two-component epoxy. A neck strap with a quick-detach clip was borrowed from an USB thumbdrive and used for carrying the phone.
TODO: A buckle/clip should be attached to the backside of the phone, to easily clip the phone to the shirt center, so it does not flap around when walking or running. Various constructions of attachments are possible, ranging from a magent and shirt-attachable piece of metal to a strip of velcro to a metal clip.
A feature definitely missing on the phone is a flashlight - a high power LED operated by a pushbutton. I have no idea why it is not a standard feature; a high-power LED is inexpensive, another pushbutton on the phone side is easy to add, and there is already a big battery inside. There are software solutions, switching the display backlight to full brightness, but that is suboptimal as it usually requires navigating through several levels of menus. Also, there's a choice between a traditional white LED, which is more usual for flashlights, and a red LED which does not kill @w|Scotopic_vision|scotopic vision and may be more suitable for quick orientation at night. I used to have that mod with an high-power amber LED on a Dancall phone and it was surprisingly practical.
Attachment of the strap holder