As a happy owner of Delta printer I was pretty concerned about repeatability of endstop switch and its accuracy, as it's crucial if you want to calibrate your Delta well.

I observed several solutions replacing microswitches, all of them have its pros and cons:

microswitch:
+low cost
+simple installation
+good rigidity
+no calibration required
-low precision (activation hysteresis not stable)
-clicking sound
-requires physical contact to activate

optical endstop:
+high precision
+contactless
+high speed
-requires powering
-requires special light interrupting "fin" on axis
-sensitive to light, requires enclosure (factory ones usually already enclosed)
-tricky to assemble yourself, factory solutions are somehow pricy and might not be the best fit for your particular setup

TMC sensorless homing:
+no extra hardware required
+it works
-to my experience it's really fiddly to adjust sensivity
-if sensivity set rather low to ensure correct homing, axis hits endstops rather hard, and it could led to hardware degradation

hall sensors:
+contactless
+precize
+easy to assemble
-requires power
-requires magnet on carriage

So I decided to give it a try. After exploring aliexpress for available factory solutions I found only Voron design, which is quite overengeneered and pricy for me. After a brief search I found Infineon IC hall sensor, which incorporates several features I need:

-extremely low cost (about 0,5 USD per unit);
-integrated design with minimal external parts required;
-decent presision

So, what you need to craft this endstop:

1x TLE4905HALA1 (4905 is must, as other will not work as intended);
1x 0805 SMD 1,2kOhm resistor
2x 0805 SMD 4.7 nF capacitors
3x wires of required length, I used wires equivalent to 36 AWG
1x JST-XH 3 pin connector kit
1x magnet (I used round 3mm diameter and 2mm tall neodym magnet)

The "face" part of IC is one with smaller square, this is sensitive part. if you looking at it, from left to right will be your power pin, ground pin, signal pin.
You should solder capacitors right between power and ground as well as ground and signal pins. This two capacitors are visible on provided photo. Resistor should be soldered on the other side between power and signal pins (outside pins). It's a little bit tricky, but doable, take your time and you'll get it.
Second, you should solder wires on IC legs, and isolate them. I used thermal shrinking tube for that. Then crimp the connector minding the polarity, and it's time to test.

Plug in the endstop into printer board, go to firmware you use, and check switch state. If it show "active" you need to change this in firmware, active = low, inactive = high.
Next, bring the magnet close to endstop and check again. If nothing changed - turn magnet around, IC is sensitive to magnet field polarity. Mind the polarity worked for you and place magnet on axis carriage with the way you like.
To my experience, 3mm dia and 2mm tall neodym magnet activates endstop as far as 5 mm to endstop. If you using stronger magnet, distance might be bigger and vice versa.

That's it. I attached STL for my delta setup, it fits perfectly with linear rails and standard chineese carriages, all I was required to do is to drill threads 2 mm deep, and press magnet with table vice.

Happy 3d printing and safe, precision homing!

custom delta

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