My setup is very compact. I use a box from a old motorola modem 6"x6"x2" which I cut a window for the LCD (1st pic). The 2nd pic is my previous version but very close to what is running now.
Components:
1. Arduino nano controller is attached to the bread board
2. LCD 20 columns x 4 rows on top
3. 8-channel relay for turning on/of what ever device you have. I am running 2 lights, 2 cooling fans, 4 solenoids for top-off
4. DS18B20 water temp sensor is attached to the black lead.
5. The white rectangular piece on upper right corner is the DHT22 air temp and humidity sensor
6. Below it is the DS3231 real time clock
7. The tiny black dot on the upper left corner of the bread board is the infrared sensor used to control the device with a remote control but I have replaced it with a bluetooth device and control it with an Android app with my Samsung phone.
I hope you have at least some basic experience in electronics, electrical and C++ coding.