I bought an Imsai8080 replica from https://thehighnibble.com/imsai8080/
I had a really nice time building the kit, toggle switches and display leds look exactly like original ones. Internally is an emulation of the IMSAI 8080 based on the ESP32 microcontroller
You may also find a more faithful replica of the Altair 8800 here https://altairclone.com/ though admittedly the IMSAI with its big coloured toggles is much more eye-catching.
There's also a very affordable (< $100, including the needed Arduino DUE) workalike that pops up on eBay every now and again...I bought one: https://imgur.com/a/qntqSMG
Basically have fun playing around with it in the same way as with a real IMSAI8080... As an example look at this video on how to enter and run a small assembler program using the switches. https://www.youtube.com/watch?v=xYNAMKPBSFI
I have one of these, got it after landing my first big tech job. I learned to program on an emulator of these 8-bit computers so it meant a lot to finally get a real one.
Most people search for high level languages when learning programming. My brain worked different - I wanted to boil the complexity away and learn the fundamentals. These 8 bit machines were the simplest computers I could find to achieve that.
The joke was on me though, mine had been upgraded to a Z80 card (yay!) that unfortunately no longer worked with the front panel (boo!).
Look at that rectified power supply. The transformer is enormous, guessing about 15 kg, and the filter caps could shock an elephant. The ripple noise would have irritated open collector logic.
My father purchased and built one of the originals as a kit. There was a program that played "flight of the bumble bee" on radio using radio leakage on the S100 bus.
