While have not tried this yet, I have theorized on making my own control strips.
It was going to involve figuring an even lighting scene, and then with a macro lens set, and compensating exposure for any bellows factor, expose 3 sucessive frames of 35mm film while placing different sections of a reflective step tablet of the sort found in Kodak old data guides. Then I would have a white, a black, and a grey exposure that were made of a paper chip printed to a given denisty known numbers of half stops apart.
The idea could be expanded to take a picture of a constant intesity light source against a transluscent screen, and then meter to get middle grey, and open up the lens to meter white properly, and then close the lens aperture down to get a sucession of exposures a half stop apart.
The 'home made test strip' film should be developed with the rest of the tank full of a section of film shot 'normally' or all middle grey, I suppose. The idea here is that you don't want all of the developer acting just on a few frames to set your time, and then when you develop a full roll, find that it poops out a bit faster when confronted with 36 exposures, say, rather than just 2 or 3.
If you don't have a denitometer, then there is the possibility of using an enlarger as a light source (standardize the aperture, lens, head height, and no dichroic filtration) and then use a camera or light meter to measure the light falling on a white card placed on the base board lit only by the enlarger's output. If using a camera, or light meter, work up a jig so that it 'sees' the same thing every reading. Note the meter reading for the black, white, and any greys, and work out what the exposure product is, take it's log, and plot it.
Not the easiest thing to do, but where circumstance demands, and the proper tool is not at hand, improvise.
The other option to judging developed test film sections density is to buy a 1/3 stop (0.10 step) transmission step wedge, and use it to visually compare your greys and white and black to it's known denities while looking though both against an evenly lit translucent surface masked to only show you the step wedge one step at a time, and your test speciment immediaty adjacent to the step wedge window. You may be surprised with a calibrated reference how well your eye is able to match densities.
