My ESP32 board has 30 pins and measures about 29mm x 52mm. I had to remove the pins to make the whole assembly thin. I wasn't happy with how large the other enclosures that I could find were. I also didn't find many cases that fit the LD2420 module. 

I placed the PCBs side by side so I could bridge the 3.3v and GND.

My modules had firmware 1.5.9. The case press fits, you may want/need to drill the holes to get it to fit.

Here's my yaml for configuring the board with the wiring shown (for my firmware) in the photos for anyone that wants to skip the learning stage of doing one of these.

uart:
  id: ld2420_uart
  baud_rate: 115200
  tx_pin: GPIO16
  rx_pin: GPIO17
  parity: NONE
  stop_bits: 1
ld2420:
text_sensor:

platform: ld2420
fw_version:
  name: LD2420 Firmware

sensor:

platform: ld2420
moving_distance:
  name : Moving Distance

binary_sensor:

platform: ld2420
has_target:
  name: Presence

select:

platform: ld2420
operating_mode:
  name: Operating Mode

number:

platform: ld2420
presence_timeout:
  name: Detection Presence Timeout
min_gate_distance:
  name: Detection Gate Minimum
max_gate_distance:
  name: Detection Gate Maximum
See "Number" section below for detail
gate_select:
  name: Select Gate to Set
still_threshold:
  name: Set Still Threshold Value
move_threshold:
  name: Set Move Threshold Value

button:

platform: ld2420
apply_config:
  name: Apply Config
factory_reset:
  name: Factory Reset
restart_module:
  name: Restart Module
revert_config:
  name: Undo Edits