This guide describes a way to build an adult-size diaper with a design very similar to existing toddler diapers.
The idea is to join 6 toddler diapers into a single one. There are some pro’s and con’s of this approach:
The idea is to take those 6 diapers and join them in the following layout:
So, the idea is to make two groups joining 3 side-by-side-by-side, and then join those one in the front, the other in the back.
The result will look something like:
About what diapers to pick the ones targeted for children around the age of 2 years (~15kg/33lbs) are the best in terms of size/absorbency/price. The next size gets ridiculously expensive and it doesn’t get much more absorbency.
Also, I haven’t tried with all of the diapers, but you will need to find some that will hold the SAP when tearing out the elastic bands. I’m using a cheap white-label ones and they seem to work perfect: cheap, absorbent and resistant.
Hot glue is perfect for this because it creates a watertight seal, and it’s really strong when it cools down.
Let’s start by preparing the front group. Lay out 3 of the diapers one next to the other
Now we need to tear or cut the elastics all the way from the front to the back, but only on those sides that will need to be joined. So on the first diaper we remove the elastic of the right side, the second we remove both, and on the third one we tear only the left side.
Keep those elastic bands aside for later. Then cut off the elastic band at the back, it will make glueing easier
And cut both tapes on either side of the group. Make sure you keep the full tape, as we’ll need it later
Now we’re ready to glue the front group together. Looking back at the arrangement diagram:
We can see that what we want to do is have the sides at the top, and the middle one underneath, so pee will flow from the sides to the middle.
For glueing there’s just one rule: Never ever glue something on the absorbing section of the diaper. It doesn’t create a seal and it’s a weak point.
The idea is to have glue all around the inner side of the diaper in the middle, and have it glued on the outside of both side diapers.
We need to have some overlap, otherwise the front will be way too wide. For my waist (85-90cm) I’ve found the most comfortable overlap is to have the very front overlap ⅓ on each side, and the back an overlap of ½.
To clarify, the following picture marks in red where the glue is at:
Start by one side, adding a string of glue to the inner face of the middle diaper all the way from the top to the bottom
Then take the diaper of that side, and stretching it out, put it over the glue by respecting the overlaps and press hard where the glue is to join both surfaces together. Make sure both diapers are in the same orientation, you don’t want to have one of them upside down. After turning it around it should look like this:
Turn it around again and repeat the same process for the other side. The result should look like this:
Now the first group (front) is ready. Before joining the back group, there’s an optional step we can do: if it’s possible, remove the tape landing strip of the front diapers and save it for later:
This will give us some stronger tapes later on.
Now we need to repeat the same steps we did on the front for the back group, but now looking back at the diagram, the overlap is different: On the backside there should be only the enough overlap to glue the diapers together, and on the front the same ½ overlap on each side.
Another difference is that you also want to glue the front part of this group, where the diapers overlap, just to have it sealed. The end result will look like:
The next join is simple: We’ll put glue on the back group and join it to the outside of the front group. Now, the amount of overlap you need is different based on the diaper you’re using and your body size.
There’s two ways of measuring this: mathematical or practical.
If you want to be mathematic, put on some underwear, take the measuring tape and measure from your navel to the back, on the same height as the navel. On my body that measured 75cm, so we’ll use this as an example.
Next measure the length of the diapers - you can use any of the diapers in the middle to measure them. My diaper measured 46 cm.
The overlap you’ll need is easy: subtract your body size to twice the diaper length: 46*2 - 75 = 17cm in my case.
The practical one is to take the back piece, put it on your back at the waist, stretch it down your legs and feel where does it reach - and remember this position. Then take the front group, put it on your front at the navel size, and then stretch it down your legs. Now based on the previous check, note where the back piece would overlap with the front piece.
Now that you know your overlap, you want to mark this spot in the outside of the front group with a pen or something. I advise having a bit less of the overlap you’ve measured just in case, around 3 or 4 cm less of overlap: If your overlap is too much you’ll have a diaper that doesn’t fit at all, while if you have too less overlap it will just sag a bit, so better be safe than sorry.
Now using a knife cut some slits on the outside of the front diaper, from a bit of margin for your overlap mark to the very back end of the group. This is only so the pee flows better from the front group to the back.
And now we’re ready to glue. Prepare the front group by putting it on the table, outside up. Then add some glue to the inside of the back group, grab it and glue it on top of the front group.
The elastics will be a bit annoying at this point. You can also add glue and join step by step (e.g. first one side, then the middle, then the other side), but make sure you leave no gaps on each step. Both parts joined will look like:
(The front is at the right, the back is on the left) To finish it up we just need to join the elastics. Start by cutting the excess on the join. Make sure not to cut into the absorbent section, otherwise the SAP will leak out!
Now take one of the elastics you teared previously, and cut the tape off
Now glue the end of this elastic where one of the outer elastics ends, on the inside
Once that’s glued in place, add a glue string from that point to the other group, up to the elastic on that group. Then stretch the elastic you want to glue as much as you can and glue it - Hold it for a few seconds for the glue to cool down before letting it go. End up by trimming away the elastic that wasn’t used.
First try to glue the landing tapes you removed from the back group just below the ones in the front group. Make sure that the original side of the landing strip will face the correct orientation and add glue all around it
On my diapers it stuck really well, so I can use double tape. Otherwise you’ll be able to just use one.
Now we need to join the tapes together by layering them together. You should have plenty of spare ones from the sides you’ve removed, so here are some possible arrangements:
With my waist size (85-90), just one level of tapes would be enough, but with two I can stretch it so it reaches the middle. If you have 2 landing tapes, I suggest you do get an arrangement with 2 tapes, it will be stronger
In these diagrams, the tape 0 is the one already attached to the diaper, the other ones are the ones we need to glue. Just add one string of glue where the tape would be attached and glue it to the respective place on the outside, making sure all the tapes are facing the same way.
I took the arrangement of 2 tapes, and it looks like this:
And that’s it, we have our diaper now ready to be used!
As a final tip, I found it useful to also stick the tapes that are underneath (so the ones on the first level): It holds the sides of the front together.
