I see you have also a Neoden4, may be we can share experiences and problems.
This is what I have created to apply solder paste, it is an acrylic with four 4 mm metal bolts, they are in the base, the PCB and the stencil, so I do not waste time aligning the PCB with the stencil to apply the solder paste.
Years ago I bought a Stencil printer, a pretty big and heavy tool, and at the end for convenience I no longer use it, it was faster to put the PCB on the table, the sntecil at the top and align it with the magnifying glass.
Now with this "invention", I do it very quickly, everything is perfectly aligned to apply the solder paste in a very short time.
In this picture, a pair of 5mm thick methacrylate pieces, each for a different PCB, both with four 4mm holes, to insert cylindrical metal bolts. They enter well giving them with the hammer taps, and they are very firm.
One of the pins inserted in the holes of the methacrylate. These are bolts that are sold as metal spacers, in this case 4mm in diameter, 12mm long.
Now we insert the PCB, on the 4 metallic bolts that we placed previously. Everything enters as very tight, we can help with a few hammer taps, or try to throw some lubricant in the bolts, or make the holes a little larger, say 4.1mm instead of 4mm, although against tighter fit, the alignment will be more perfect.
Insert the stencil, which also has the same four 4mm holes, and fit perfectly over the bolts, just like with the PCB, very tight, you have to help yourself with some small hammer gobs.
Final step, put weight on the stencil so that it is firmly stuck to the PCB, essential so that the solder paste does not expand under the stencil, especially if we give more than one pass to extend the solder paste. I bought some time ago these four weights of 2 kg each that can be seen in the photo, which I put on the ends and they are perfect.
The alignment is PERFECT and instantaneous, this is important when we have very fine pitch chips, such as TQFQ100 or 144, because there small misalignments do not drop the solder paste where it should and then can produce shorts between pins or pins that do not solder.