As the Title says, in Mek Versions past 1.12.2 you are able to in and output from the same side.

Would be highly appreciated if it is possible to be added.

There is no way to achieve this for the time being
There may be a big overhaul of the way the slot is done

Done this without overhauling, closing the issue
If you need a file, download it here

Is it planned to merge this with Mekanism Community Edition, or is this your own Version?

And thank you very much, just tested and works perfectly !

Also, your version adds a verity of machines, also upgraded machines that arent even in newer Mek or in the newest Mek. Are you still experimenting with these machines or do you wanna add some kinda upgrades, even they arent in original mek past 1.12.2?