Build ArduinoISP programmer using Attiny84

Hi, been awhile since I posted here, Lots have changed…

I have been using Atmega328 on a breadboard to program very simple projects that utilize Atmega328p, Attiny84, and Attiny85 MCUs.

At the moment, I have a handful of spare Attiny’s, but no spare 328p. I need the 328 I'm using as ISP, for my next project, but then, how to program it? Of course I can purchase another 328p and wait for it to arrive…

Well, I thought, I'll use one of my spare Attiny’s in place of my 328p on the breadboard but found it way over my head technically.

What have I tried…? First I attempted to compile “Arduino as ISP” in the IDE selecting Attiny84 w/8mhz internal from the boards menu. (I have already set fuses and used this Attiny84 on another project).

That gave an error regarding serial…

I then remembered there is no hardware serial on Attiny (I use software serial on Attiny often through USB/serial converters) so I edited the “asISP” sketch replacing anything regarding “Serial.x” with “Software.Serial.x”.

The next error compiling was regarding “SPCR”… I think…. I did some searching and that became grossly above my experience level.

At this point, I'm just curious:

1. Can this be done…using Attiny.x as the programmer?

2. Has anyone done that can share the process?

Grateful for anyone's contribution…!

Sparkfun has an open source programmer that uses attiny84, so documentation includes the schematic, PCB files, firmware, drivers, etc.
The firmware for it is USBtinyISP, not Arduino as ISP.
https://www.sparkfun.com/tiny-avr-programmer.html

Oh nice, I did not know… I'll spend some time looking at the files there…! Thanks!!