Here you go. TTL only, unless you develop a switch to change the resistor for the display input, and use CMOS equivalent IC's.
The display will light an "H" for high, and a "L" for low. For the oscillation probing, both H and L will seem to be lit. This is due to Persistence of vision because the oscillations occur too rapidly for the human eye to distinguish between H and L displays. Thus, you'll see an "8" unless the oscillations are extremely low frequency.
I've seen some neat enclosures, which enclose the circuit in a tube which is about 1 inch I.D. or so. (PVC tubing is cheap!). The probe is fasted (Epoxy) through the center of a pvc tube cap, which fits onto one end of the PVC tube. The other end has a similar cap, with holes to allow the wires through. You can then paint the PVC tubing (Which looks nice if you do it right). After you finish, you'll have something that looks like an oversized marker, or an exploded view of a ball-point pen. The enclosure shouldn't cost more than a couple of dollars.