Logitech K400 wireless touchpad keyboard was purchased for the Common Room, but the fact that it was more portable meant that it get filthy fast, so filthproof/waterproof case was required. Nothing was available on the market, so it was decided to take the mater into our own hands.

Required items for Waterproof (Water Resistant) Wireless Keyboard Resealable Case/Bag:

Correct Size Resealable bag (Plenty of resealable bag size alternatives on eBay);
Spray on rubber (Optional, but recommended as it will make the backside surface of the case less slipper).

Steps for making the Keyboard Case/Bag:

A correct size resealable plastic bag was purchased, together with some spray one rubber.
The backside of the resealable bag was sprayed with spray on rubber. This made the resealable bag backside less slippery.
The the keyboard was placed into the ready resealable-backside-rubberized-wireless-keyboard-case.

Step 1: Purchasing Resealable Plastic Bags

Many alternative bag dimensions are available online, check the dimensions that you need and the patiently look for the best fit. I could not find the best fitting bags for the Logitech K400 (5.4 x 13.9 x 0.9 inches) on eBay as was looking for rather custom 6 x 14 inches (15 x 37 cm) plastic resealable bags, but Google search solved this issue.