That’s what I did. You can see my journey to direct drive here: [U]The journey to convert my Ender 5 Pro to direct drive. - MakeWithTech Community Forum
Hah, yeah. I know. Probably happens when the auto correction on my ipad kicks in the wrong way. Did not notice that.
Yes, OctoPrint “IS” a webserver. Thats its main purpose. No PC or SD card printing required. Just upload the file via browser or Cura and the files get stored on the SD card placed inside the raspberry pi. The nice thing about that is that you usually have a 16 or 32GB card, so you can store tons of prints on there. You even can setup folders and sort files. I have upgrade parts for my printers in folders and other stuff in the base folder.
When I need a previous print like a calibration cube or a spool mount, I simply type the name into a search field and hit print using my ipad. Since OctoPrint has a ton of plugins, you can expand its feature range quite (<<< hah, using my PowerMac G4) a bit. There even are fancy modules like a noodle detection, which aborts a print, when a print is failing unnoticed by the user. Also modules for time lapse, auto power control and external thermal runaway protection can be added with just a button click. Installing OctoPrint is easy. Just write the image to SD card and you basically are done. You may want to setup your wifi in advance and after the first boot and a little setup your printer is ready to run without any pc or tablett connected.
All my printers have their own raspberry pi, even so it is possible to connect multiple printers to a single pi. I like the fact to have them as independent devices, so I can unplug and perform maintenance without disabling/disturbing other devices during that process.
Interestingly, James @ clough42 on YT ran into a problem with having too many plugins on a Pi. It interfered with the transfer of gcode to the printer, leading to the printer hiccuping randomly and leaving blobs. If I did decide to get a Pi, I think I would insist on a model 4, to get the faster CPU.
You could go with the 3 or the 4 in regards to cpu. Octoprint is just a light weight linux image, not at all a cpu hog or even a memory hog at that. If you were to get a 3 then get the 3 B+ so you get the integrated wifi and bluetooth. Setup will nearly be the same. If I remember right the networking config files may be stored in different places. Now that I’ve typed that out I realized that is an Octoprint version difference and not a difference in Pi version. 
Really can’t go wrong with either though. We used to setup entire whole home automation systems where the master controller units basically ran off the same resources as a Pi 3 has… this was back before smart phones existed.
Well, a Pi2 or 3 works fine, too. A Pi1 is slow and needs some patience when booting/connecting/uploading files. I would consider a Pi4 overkill. Especially the bigger versions with more RAM are not needed as you only run one application on it. So if you don´t have a pi get the 39 Euro 2GB RAM version. The 4/8 GB versions cost up to 60/80$ os so and should only be bought if you consider using the Pi for other stuff like a desktop OS once in a while. I only have Pi1, P2 and P3 in use and all in the lowest spec available. However for 3D printing a Pi3 if enough and should be available second hand cheaply as many people upgraded already. The only P4 I own is used as a mediacenter with Kodi, as the new GFX blob is able to decode h265 in hardware, which the others can´t.
The mentioned hickups and blobs happen due to 8 bit printer boards and have nothing to do with the raspbery pi. Well unless you have a pi1 and upload a 10MB stl while printing. That causes slowdowns for sure. 
Get a cheap 20$/Euro Pi3 or a 40$/Euro Pi4 2GB and everything is fine.
PS. It seems this forum too dislikes my old habit of posting and repeatedly editing a post and triggered some spam delay. Happens a lot. I often need to enter a capture on the google main page due to my infamous search habits, too.
You might want to check out James’ video. It’s pretty interesting: https://forum.drvax.com/forum/3d-pri…ryone#post1947. He’s pretty certain that too many plugins on his Pi are to blame. He disabled the plugins and the problem went away.
'Course, I could always just load Linux onto my Surface, never have to worry about speed or RAM.
Of course when you enable every plugin you will need more and more resources. The question is do you need all that? Probably not.
I only enabled the module for power switching, as I have my PIs connected to a ATX power supply and the plugin for time shifts, which I barely used due to the bad camera view in my printers. However, they don´t need any cpu power. Especially the power thingy. The time lapses take some time to compose the stored images into a movie, when the print is done. Especially on my Pi1 this takes depending on the print 20-30 minutes, which is a big show stopper, when you want to print multiple prints in a row. As it moves the print head to a static position before taking a picture your print gets interrupted anyway. On the other side I did not use it much. On the TronXY with the Pi2 it only took 30 seconds or so to compose the movie, which is acceptable as I need to peel off the old print by hand anyway before restarting the printer.
For me the basic functionality of the Pis is wifi connectivity, to store my previous print files in a database, to provide a CAM so I can check on the prints from my office and auto turn off the printers, when I am not around or asleep. For that even the Pi2 is more than enough. I had those PIs flying around anyway and did not buy one for the 3d printing job. If I would need a new one right, I would check the local ebay sellers (ebay-kleinanzeigen) for some cheap Pi2/Pi3 or go for the smallest Pi4 from Amazon.
If you want a new one, the small Pi4 is the way to go anyway as the should all cost around the same and the smaller models are probably only cheaper when on sale out or so.
I would recommend the pie 4 with 4 GB of memory small increase in price and big increase in performance. Even with my pie cam set to 1920 X 1080 25 fps the resource monitor (a plugin) is staying for the most part around 10 to 18 % processor usage. It does peak from time to time at around 45 %. I have several plugins (not all by any means) and find them useful. PC’s (macs and windows machines) can get bogged down running other services/programs (updates, or whatever you have installed).
Like having a device running software (octoprint) and nothing else. Am using a dc to dc buck converter to bring the voltage of the printers power supply down to 5 volts instead of running the pie on its own external power supply.
Nice! I was just looking at ways to utilize the printer PSU for the Pi as well. Are you still able to configure wake on LAN, or have you even attempted that yet?
I have a samsung smartthings home automation hub so am using a smartthings smart wifi plug that can monitor power usage going through it. I have the printer plugged into it and set automations so when the power rises above 50 watts then falls below that level for 5 min to shut the plug off which turns off the printer and pie. Have a plugin on octoprint so when the print finishes it does a software shutdown so no files get corrupted. Can turn on/off the smartthings plug with their phone software from anywhere. Am doing and monitoring a print now while at work
That’s certainly convenient. I’m too concerned about security to implement IoT devices. I guess I spent too many years doing IT security.
I am a Network and security IT tech for a large company were i live i know how to secure private networks. A hardware VPN device is a very good way to protect your network. Nobody gets into my network without me knowing about it first. I’ll know about the attempt long before they get in and can take measures at that point to prevent it. As you know a very big part of protecting a network is detection.
Absolutely! Detection is key. No doubt hardware VPN is a good sol’n. However, unless things have changed drastically, it’s a bit pricey for most consumers.
I did once set up a hardware VPN for a telephone extension system. They were expanding, so they were moving a number of employees to a nearby building. My task was to find a way to connect those employees to the main corporate PBX. Eventually I did it by using several 128K ISDN lines. It was a bit tricky getting the VPN hardware to accept ISDN lines, but I managed to make it work. The employees could not tell they were not at the main building.
Yes they can be expensive i have a sonicwall (about 400 U.S.) very nice VPN/firewall device. I have 1 gig fiber (up and down, unlimited data transfer)) here at home so i wanted good protection.