Summary

I have seen many quick-fit systems for extruders, but many does as one whole part with hot-end below. I don't like it very much, thus i have designed better version to keep hot-end part seperated.

Instructions

Update 1: After some testprints i see some STL files are not good enough. Extruder misses the 4mm filament hole. Next days i will try fix the problems. The carriage part has lucky no problems.
The hot-end holder block needs a small fix, because the hole is a bit too wide.

Update 2: Extruder 01 and 02 are checked on errors (thanks to netfabb studio) and verified in Repetier-host. Now it's confirmed it has filament hole and surface is corrected, i have now uploaded fixed version. You should not have problems with fixed versions. Have fun with printing.

I have seen many quick-fit systems, but so far i can see, all systems have hot-end part fixed with the extruder part. Which means if you remove the extruder, the hot-end part will go also with extruder. An one big part.
And also, if you want change between 0,35mm and 0,5mm nozzle, you need two stepper motors, two extruders and that is more material you must print and build.

But we can try with just one extruder and one steppermotor. Only 2 blocks are printed for the hot-end part. If you have own hot-end, you make just only custom block for it to fit in. Much smaller and easier.

I have already designed everything in Sketchup after many tries. Now the design is completed, i can now test the system. Just wait for the more real photos and (perhaps corrected) STL files.
You can now take al look at the Sketchup images to see my idea. You are free to check my system out, but STL files are not checked in real use. I'm still busy with printing.

Explaination about system:
The green block part inside new designed carriage is for hot-end part. The hole is for PFTE isolator which is around ~17mm diameter. It is fixed with 2 small screws at both sides.
The block will fit almost exactly inside carriage.
The extruder part will slide inside yellow block and the yellow handle keep it on the place.
The yellow handle is mounted with 4mm bolt. The yellow block may mounted with bolts but may also glued on the carriage.

The extruder is a bit redesigned but it has 2 designs in one:

http://www.thingiverse.com/thing:5401
http://www.thingiverse.com/thing:27322
The carriage is based on LM8UU carriage http://www.thingiverse.com/thing:12481 but is customized for new system.
Below carriage i have also redesigned clamp system to hold LM8UU on place. No tiewraps needed. Just a small screw and it will keep on place.

The carriage has also holder for the fanduct, which is redesigned for my carriage and hot-end.
You may give some reactions about my idea with separated hot-end block and extruder parts in Quick-fit system.

Made with Google Sketchup after many days....

Another Quick-Fit Extruder system