It can be built into the tiniest of boxes and requires only a 9-volt battery to power it. Construction is simple, although care must be taken to insure that all leads are as short as possible. L3 should have its iron-core slug removed. To check their efficiency, use a grid dip meter to see if you're anywhere near 144 MHz. It should resonant at your operating frequency.
Main thing is to get the crystal to oscillate.
From here on in you can simply tune for maximum signal using a GDO, field strength meter, or receiver S meter. If it doesn't, adjust number of turns. The positive pole of B1 goes to ground. I attempted to use arrows to indicate the adjustable coil forms. Nothing was said about the two taps coming off of L2 - you'll have to experiment as to their placement.