Can you take and elongate the whole structure and then put some open space between the part that goes in the grouphead and the part that holds the bolt, so you can stick something up in there to push in the seals so you can also use it to put piston back in?

Something like this,

So I finally had the time to try out the 3D printed tool...and well, it didn't work at all. It separated into two pieces as soon as any significant amount of force was applied to piston face with the bolt. I ended up using a clamp with no major difficulty. The ring that guides the seals back into the group was handy though.

Good news is that the Export is performing very well again! I was having issues with the lever slipping, and drawing coffee back into the boiler. I used a nylon bicycle tire lever to aid in getting the new seals onto the piston without damaging either the seals or the piston.

I just noticed that you can rent a similar tool from 1st-Line for about $35 for 14 days:
https://www.1st-line.com/store/pc/Servi ... 6p8082.htm

As I said before, if you dont create this 3d printed part with a quality material like ABS, then you face issues with breakage.
I have used my version of the tool for 6 piston removals and re-assembly. The small ring tool does help to load in the seals, I use a paper clip to pierce the hole that appears at the top of the group sleeve, with a good push upwards.

I'm going to try this with a work printer using carbon/nylon as its the strongest option we have. I'm worried the "ears" will fail. I'll let y'all know how it turns out. This is my first post so I'll add photos if I'm allowed. Thanks to Sprint Jinx for sharing the design files!

This piece does not seem to be under too much stress - in the very worst case if it breaks it will just fly downward with a bit of impact. Wear safety glasses and try putting something shock absorbent like a piece of foam under the tool in case it breaks,

Ideally one could make one from a regular portafilter by just threading a bolt through the bottom center.

I bought one from Lamacchinacaffe in Italy, and I must say it changes the job from a big hassle to a non-issue. Accessing the piston now is as easy as turning a screw, and takes about as much time as hand grinding 15g of coffee.

Good News! I used the version 3.0 3d printed PF tool and gasket sleeve with great success (printed with carbon/nylon). I don't have replacement seals yet, but I decided to practice.
That's right, I completely removed the piston and reinserted it just for fun. It was a breeze. This is the perfect tool for the job (The paper clip is helpful during removal of the sleeve, it holds the piston in after the middle seal has just entered the group). Thanks again sprint jinx!

I did have an interesting development; let me start by saying I just bought this machine used (2 years old with supposedly frequent use) and haven't pulled a good shot with it yet ( I've tried 5 so far). Previous machine was a cheapo delonghi EC155 with naked PF.

Oddly, the first pull after removing and reinserting the piston was much improved. The lever returned to home very slowly as it should. The lever was returning home quickly before, which is why I thought it needed new seals somewhere. The second pull behaved just as before, the handle returned home quickly. The shot was okay because the first pull extracted some crema. Maybe this symptom is from a different issue? In any case, new seals along with a thorough clean and regrease of the piston assembly shouldn't hurt.

highly likely all that is wrong with your machine is worn seals- replace with new ones and a lube and all should be good.