I've always liked the Attiny & when Spence Konde (aka DrAzzy) came along with the MegaTinyCore I had to give it a spin! I love it!
I kicked off with the 412 but its lack of pins makes debugging quite frustrating, so I looked at the 1614.
I would have bought one of DrAzzy's excellent ready rolled boards were it not for the postage cost! so I designed my own dev board. Fundamentally it's very simple.
All of the 1614 pins are broken out to female headers in lieu of a breadboard.
There are four I2C headers. Many I2C modules use a 'standard' Vcc-GND-SCL-SDA pinout. I've used this approach before & it's very useful.
There is a 'standard' ft232 connector & traditional Arduino reset circuit to work with the omniboot loader.
A switch is used to isolate the UPDI/RESET pin.
Apart from the 1614, everything is through hole soldered with bog standard components
I'm so pleased with this that I'm selling it!
Shipping charges are a problem with things like this but our strange UK postal service lets me send things thinner than 5mm & weighing less than 10g at a reasonable rate.
I'm thinking that £4 for two bare PCBs is reasonable? Postage costs would be £2 anywhere in the world.
Is this of interest?