Because it is quite expensive, but not too hard to make one yourself, I decided to contribute another instructable.
4 pieces of 255 mm * 140mm * 9 mm (10" * 5.5" * 3/8") in nice solid wood (I used Oak), these will be the sides of the box
1 piece of 130mm * 130mm * 8 mm (5" * 5" * 3/8"). this will be the bottom, invisible and so it can be some MDF or plywood
~2000 bamboo skewers, 25 cm long (9.8")
Saw : only needed if you need to cut the 5 pieces yourself
Sander : ideally a Belt sander (I use the Bosch PBS 7 AE) for rough sanding, and a Orbital Sander (I use Bosch GSS 280 AVE) for finishing
Router (optional, I use Bosch POF 800 ACE)
Effort : takes about half a day
Cost : about 30$ - 25 euro. The Bamboo skewers I bought were 0.85 euro/100 pcs
You could modify the dimensions if you want to : I just made it to the size of some Oak I had left over, and the final result is about the right size for 3 to 6 knives.