I started making drop-off indicators a few seasons ago, because I wasn't happy with shop-bought versions. It took a little trial and error to get them right, but once I'd got my head round the two main problems, they were simple to solve.
Problem one was that the plastic clips they came with were fiddly to adjust and - potentially worse still - had a nasty habit of sticking to braid. That meant drop-backs didn't always register promptly. The other drawback, which compounded the first problem, was that they weren't heavy enough.
I cured both problems by using Solar ball clips, which being made of metal, didn't stick to the line. They were also far easier to adjust and didn't slacken off once you'd got the tension right. Solar also make heads, which take screw-in weights.
I originally thought this would be useful, as I could adjust the weighting. Before long, I just stuck to the heaviest weights, which are around an ounce. Fish tight, with the drop-off right under the reel, and they'll ping off the line as soon as you get a pull. You can tighten the clips when fishing in wind, flow or undertow.
The weighting means the set-up will register a drop-back, while the ball clips don't stick to the line, meaning the indicator will drop, pulling line through the alarm, meaning you'll hear it go when a fish comes towards you.
I don't buy into this idea that if you use a heavy enough lead on your rig, a pike which comes towards you will still register by pulling the line out of the clip, due to some pulley effect. In my experience, the fish moves the lead most times, meaning the line slackens and the weight on the indicator makes it show a drop-back.
The stem of the incicator is just a cane barbecue skewer you can buy for peanuts. I glue a rig sleeve to the end so it screws into the thread on the weight. It looks a bit ramshackle, but they stay put for months. If I break one, I just stick another cane skewer in.
At the other end (not shown...), there's a bit of thick silicone runner to make a hinge, attached to the time-honoured Terry clip. The heads and weights cost around £10 an indicator - or they did when I made these. Once you've bought these bits, they last forever unless you lose them or your mates nick them.
I always use a front alarm, usually one of the budget variety, because at £20 a throw, it's not the end of the world if you lose one or drop it in the drink. It also means I don't have to use different alarms for legering and float fishing.