Hello everyone! My apologies to those metric people around the globe, but this project is in imperial units. I am not opposed to metric at all, but all the material I used in this project are those items I already had on hand. 

Some time back, I had made a PCB holder made of wood and it would never set proper on a flat surface, but it did get the job done none the less. It used steel rods for adjustability that were salvaged from an old printer. So I decided to give my old design an upgrade and the new design sets completely flat on my bench. I repurposed the steel rods from the old one, but that was all as everything else is new and/or re-designed. So if you would, please follow along with me and I will give you all the details on how you can make one for yourself. This is not meant to be an “Instructable”, but rather some of the steps and the hardware that I used which should be commonly available at your local hardware store. Be aware that this project requires captive nut printing.

This PCB holder can handle quite large boards provided the proper steel rods that you use are long enough. Mine are 10.75" long. I don't have a need for boards much larger than 6" square anyway, but the longer the rods, the larger the boards it can handle. The distance from the center point of the board grips to the steel rod is 5.75" so this can accommodate boards up to near 11" wide and still be able to rotate 360°. The steel rods required need to be exactly 0.5" diameter. Best to use stainless steel if possible. 

All bolts and nuts used are ¼"-20 and suggest using bolts with partial thread (better for the spring action) and not use bolts with all thread. The springs should be found at most hardware stores. The springs cannot be larger than 3/8" because the pockets on the end plates and the boards grips are .38" in diameter. If you cannot find the same length spring as I have used you could substitute the longer bolt for a shorter one as well as for the springs. I just used what I already had on hand. The photos show what lengths I used only as a guide. However, I would advise that you not use a stiff spring as it could deform the end plates, cause inserting board onto the grips harder and also make turning the knob with the detent much harder and possible wear on the detents. You should be able to estimate for yourself what kind of tension to have. Too little tension could cause the boards to just fall out of the grips. FYI: Total depth inside the board grip part is 1.128" from the outer most surface so you will have quite a bit of travel for a bolt. Most thread lengths on the partial thread bolts are usually less than 1" and will not have to worry about bottoming out.

Here is a list of the materials and the quantities.

•  1      ¼-20 X 3.00" 
•  1      ¼-20 X 2.25"
•  4      ¼-20 X 1.5"
•  4      ¼-20 standard nut (.218" actual thickness)
•  2      ¼-20 nylon lock nut (.327" actual thickness)
•  1      3/8" X 1.75" spring
•  1      3/8" X 0.5" spring

A word about captive nuts. If your nylon nut is thicker than what I recommend or have shown as the actual thickness, then you will need to file down to the specified thickness. If less than the specified thickness, then you might try placing a piece of paper below the nut to shim to proper height. NOTE: For those that are not experienced with captive nuts in a printed objects, may I suggest that you do not touch the nut with you bare fingers as it will transfer oils from you fingertips onto the face of the nut and the filament will not adhere to the nut thus causing a glob to form and more than likely a crash on the print head. Prep by taking the nut and clean with alcohol then apply glue stick to the face up. Use either a paper towel or rubber gloves to hold the nut. After applying the glue stick, take one of your bolts and partially thread the nut on and have ready before starting the print for the board grip. Once the print has started, place the nut and bolt onto the heated bed away from the print head while the part is being printed. Heating the nut will help the filament to adhere to the nut surface. When the part is paused and ready for the nut to be inserted, take the bolt and shove the nut into the pocket and unscrew the bolt. Be sure to clean away any oozing filament from the nozzle before you resume the print. Doing so will ensure a clean start on resume preventing any globs that might attach which could cause a fail. 

I have provided a few extra print files for the board grips to use on both MK3S and the Mini. I have found that the mini worked best for me printing the board grips with the captive nut because your able to see the print nozzle as its re-starts from pause after placing the nut into the pocket, but it will work just fine on the MK3S as well. 

I have also included several .3mf project files. Use them or not, does not matter to me. For those who are new to 3D printing, I suggest using the project files for the knobs. I have included supports in the hex pockets. Without them you may have problems getting the heads of the bolts to seat down inside properly. If they are not seated proper then the hex plugs will not seat flush to the knob surface. I suggest that anyone using the .stl files make sure supports are painted on inside the hex pockets. The supports pop out pretty easy by ramming the bolt through the opposite direction. I just gave it a quick tap with a small hammer and they popped out clean.

That's all I have and I hope that this project may find its way into your shop/lab and be of some use to someone. Take care ;p