Update: It appears that some few users had difficulties with a too tight fit of the retractable part. This may be because razor blades come in different thicknesses: #9 (0,23 mm/0,009") and #12 (0,30 mm/0,012"). I have added a plate with a #12 version of the retractable part. 

This is my design for a bread lame. It had to have the following attributes:

• No other parts needed other than the razor
• Kidsafe
• Easy to clean

So this is what I'm using now. The base design originates from your ordinary cutter knife but uses a razor blade. The holder resembles the inside of the blade for perfekt grip and hold and is shaped in a way that it protects the housing from getting filled with dough when slicing the bread. 

This makes it easy to clean even without disassembly. 

This assembly is then inserted into the body and the Screw and Nut are used to keep it into position. Loose the screw lightly to slide it back and forth and tighten them either when slicing the dough or when the blade is stored inside the body. 

Make sure, that you place the nut with the round side away from the opening so the blade can fully disappear in the body. 

Screw and nut are sized in a way that the whole lame is easy to disassemble for cleaning.

This is the lame in action on a sourdough bread and below you see the result. If anyone is interested, I can share the recipe :-)

I hope you enjoy this little gadget as much as I do.