For all parts except lock top, I recommend 100% infill for maximum strength.
Step 1: Spring Lever
Place the spring lever on the pin shown. The spring lever should move freely on the pin with minimal friction. If the spring lever moves stiffly or does not fit, clean the pin and hole with sand paper or file until a smooth fit is achieved. WARNING: any forceful twisting on the pin could make it break off.
Step 2: Tongue Placement
Before placing the tongue, rub it generously with bar soap on all sides to reduce friction. Place it in the slot with the end groove at the approximate location shown.
Step 3: Spring Placement
Place the spring as shown so that the top fits into the groove on the tongue, and the bottom is pushed down as far as possible into the groove without damaging it.
Step 4: Function Check
Push on the spring lever as shown and ensure that the beveled end of the tongue retracts as shown. When the spring lever is released, everything snaps back to the original position. If it does not, try rubbing more bar soap on the tongue, and possibly on the bottom of the spring lever.
Step 5: Shackle Placement
Place the shackle on the pin shown. The shackle should be able to twist freely on the pin. If there is excess friction, clean the pin and/or hole with sand paper or a file.
Step 6: Function Check
Twist the shackle into the closed position. It should snap into place, with the beveled end of the tongue locking it. Place the key on the pin below the spring lever and twist as shown. With the tongue retracted as shown, the shackle can be swung open. Lock and unlock several times to ensure there is no catching.
Step 7: Key fit check
Before putting the lock top on the lock, insert the key through the key hole to make sure it fits.
Step 8: Putting on the Lock Top
Install the lock top on the 4 pins shown. The pins should fit tightly, but if the fit is too tight, clean the pins with sandpaper or a file, being careful not to remove too much material.
Note: once the top is placed, it is difficult to remove without breaking the pins.