Requirements

• Easily found when misplaced
  
• Big enough to hold easily but not too big that it's cumbersome
  
• Should have a battery compartment so that unskilled personnel can replace batteries without having to open up the housing
  
• Room enough for the necessary buttons
• Nice looking housing, attractive appearance
  

Selection

Hammon Manufacturing offers a wide range of suitable housings in their 1553 series.  Chinese copies are available from SZOMK: AK-H-30 series.

Selecting color

• Gray/black : dull, hard to find when misplaced
• Red : red color relates to danger or things that are hot.  Preserve this color for objects that are dangerous/hot.
• Translucent blue : useful for white or blue LEDs on the PCB.  No need to drill extra holes in the housing.
• Yellow : perfect color

Selecting size

There are two options for a yellow case with a battery compartment:

• 1553BYLBKBAT: 117 x 79 x 24 mm : €7.72
• 1553DYLBKBAT: 147 x 89 x 25 mm : €8.24 : will leave more room for buttons

Accessoires

ABS blocks NIR.  Hammond Mfg. provides a PC (polycarbonate) window : 1553DIR-BULK.  This part can't be bought from the usual online resellers.  It might be better to find a piece of PC with the correct thickness and laser it.  Another option is to keep the current ABS panel and drill a hole for the LED in it.

Battery compartment

Room for two AA-cells, or one PP3 9V battery.  Two AA-cells will be used here because they offer the highest energy per dollar.

Conclusion

1553DYLBKBAT : IP54 Handheld Enclosure, ABS, Yellow, 147 x 89 x 24mm