This project contains a box to hide the nodeMCU esp8266 together with a 0.96" oled display. The box is then connected to an external usb power supply that is on the nodeMCU board.

First, the nodeMCU board is slid into the bottom box on four sticks, attached with a melt gun, and then the display is attached to the lid using a melt gun. The lid is slid onto the box. The box can be attached anywhere using double-sided adhesive tape. The lid can be removed from the box at any time.

If you want to use this case as it is in the photo to display PV data from a Solax inverter, you can download the source code below. You will need Home assistant and the ESPHome add-on installed for this. You can also use the icons, which are also downloadable.

esphome:
 name: photovoltaics
 friendly_name: photovoltaics

esp8266:
 board: nodemcuv2

# Enable logging
logger:

# Enable Home Assistant API
api:
 encryption:
   key: "yourkey"

ota:
 platform: esphome
 password: "yourpassword"
#  num_attempts: 3
#  safe_mode: no

wifi:
 ssid: !secret wifi_ssid
 password: !secret wifi_password

 # Enable fallback hotspot (captive portal) in case wifi connection fails
 ap:
   ssid: "Photovoltaics  Fallback Hotspot"
   password: "password"

#switch:
#  - platform: gpio
#    pin: D4 #interni led
#    inverted: True
#    name: "NodeMCU internal LED"
#    id: internal_led

time:
 - platform: homeassistant
   id: homeassistant_time      
   timezone: Europe/Prague

image:      # The folder for images is (create) on HA in \config\esphome\_icons
 - file: "_icons/pv.png"
   id: imgPV
 - file: "_icons/bat.png"
   id: imgBat
 - file: "_icons/grid.png"
   id: imgGrid
 - file: "_icons/house.png"
   id: imgDum

sensor:
 - platform: homeassistant
   id: fve_production
   entity_id: sensor.solax_pv_power_total
   internal: true

 - platform: homeassistant
   id: fve_consumption
   entity_id: sensor.solax_house_load
   internal: true

 - platform: homeassistant
   id: fve_battery
   entity_id: sensor.solax_battery_power_charge
   internal: true

 - platform: homeassistant
   id: fve_battery_soc
   entity_id: sensor.solax_battery_capacity
   internal: true

 - platform: homeassistant
   id: fve_grid
   entity_id: sensor.solax_grid_import
   internal: true

font:
 - file: 'arial.ttf'
   id: font1
   size: 13

 - file: 'arial.ttf'
   id: font2
   size: 12

i2c:
  sda: D2
  scl: D1
  scan: false

display:
 - platform: ssd1306_i2c
   model: SSD1306_128X64
   address: 0x3C
   id: my_display
   lambda: |-
     it.image(0, 2, id(imgPV));
     if (id(fve_production).state <= 999) {
       it.printf(15, 0, id(font1), TextAlign::TOP_LEFT, "%.0f W", id(fve_production).state);  
     } else {
       it.printf(15, 0, id(font1), TextAlign::TOP_LEFT, "%.2f kW", id(fve_production).state/1000);  
     }

     it.image(0, 19, id(imgDum));
     if (id(fve_consumption).state <= 999) {
       it.printf(15, 33, id(font1), TextAlign::BOTTOM_LEFT, "%.0f W", id(fve_consumption).state); 
     } else {
       it.printf(15, 33, id(font1), TextAlign::BOTTOM_LEFT, "%.2f kW", id(fve_consumption).state/1000);  
     }  

     it.image(0, 35, id(imgGrid));
     if (id(fve_grid).state <= 999) {
       it.printf(15, 49, id(font1), TextAlign::BOTTOM_LEFT, "%.0f W", id(fve_grid).state);
     } else {
       it.printf(15, 49, id(font1), TextAlign::BOTTOM_LEFT, "%.2f kW", id(fve_grid).state/1000);
     }  

     it.strftime(0, 51, id(font1), "  %d.%m.%Y   %H:%M", id(homeassistant_time).now());

     it.image(116, 2, id(imgBat));
     it.printf(115, 0, id(font1), TextAlign::TOP_RIGHT, "%.0f%%", id(fve_battery_soc).state);

     it.image(116, 19, id(imgBat));
     if ((id(fve_consumption).state) >= 0) {
       if ((id(fve_consumption).state) <= 999) {
         it.printf(115, 19, id(font2), TextAlign::TOP_RIGHT, "%.0f W", id(fve_battery).state);
       } else {
         it.printf(115, 19, id(font2), TextAlign::TOP_RIGHT, "%.2fkW", id(fve_battery).state/1000);
       }  
     } else {
       if ((id(fve_consumption).state) >= -999) {
         it.printf(115, 19, id(font2), TextAlign::TOP_RIGHT, "-%.0f W", id(fve_battery).state);
       } else {
         it.printf(115, 19, id(font2), TextAlign::TOP_RIGHT, "-%.2fkW", id(fve_battery).state/1000);
       }  
     }
captive_portal: