This is a VERY simple K'nex screwdriver, You can carve the screwdriver end into something like a straight-blade. If you like this, please don't forget to vote!!
Step 1: Build the Handle
The handle is just 2 white connectors with 8 yellow rods on them like in the photos.
Step 2: Add the "bit"
Add the grey rod and put the tan clips on on both ends like the photos show.
Congratulations!! You are now done with your K'nex screwdriver!!
If you don't mind wrecking a grey rod, you can carve a straight-blade on the end of it.
Note: Don't try to use this on a real screw, it will probably not work. :)