In this instructable I show a little tool made from household materials which removes the pain from sealing a huge number envelopes or gluing many stamps on letters.

Step 1: The Problem: 50+ Letters to Send

Recently I had a lot of letters to send and the envelopes had not an adhesive seal. I don't know how you call it exactly, but the seal of my envelopes had to be moistened to become adhesive. For one or two letters normally one can do this with its tongue, but for 60+ letters this was not an option.

In addition I had to to put not adhesive stamps on every letter. I had adhesive stamps but they were valid only for standard letters and mine got heavy so I had to put some extra postage on. And those extra postage stamps had also to be moistened to become adhesive.

So I came up with this little helper made entirely form household materials: A small peace of sponge squeezed into a clothespin.
The sponge will hold the water for moistening and the clothespin will act as a shaft to hold it without getting wet fingers (and therefor spoiling the envelopes).

Step 2: Gather Materials

All you need is a (kitchen) sponge and a clothespin.

To build this little helper you 'll need a scissor or some (kind of x-acto) knife/cutter. The knife works better since the scissors will squeeze the sponge more then it will cut through it. I started with a scissor but change to a (sharp kitchen) knife.
A non permanent marker will also be handy.

Step 3: Mark and Cut

First mark the volume you're planning to cut out.
To mark this cutout volume hold your clothespin on top of the sponge and mark the width of the clothespin.
The length and depth of the cutout depend also on your clothespin. Just remember you only need a little tip.

Then cut out the volume along the marked lines.
If there are leftovers from the marker on the cutout then wash it to get rid of it. Otherwise you'll spoil the envelopes later.

Step 4: Assemble

Assembling is very easy since you only have to snap the cutout with the clothespin.
Just let a little bit of the volume peek outside the clothespin. With this top (of your tool) you will later apply the water to the surface of the envelope seal/stamp/whatever you need to moisten.

Step 5: Glue

The instructions in this step is kind of optional and depend on you "working" environment.
I'll share my workplace setting since i think it is a common one ...

Working on our dining table I used a dishtowel as a base to keep the table dry and to have a base which can be altered very fast if wet.

To seal the envelopes first dip the sponge into the water supply and then drip off the sponge on the saucer. To moisten the gluing surface it is sufficient if the sponge holds only a little water. If the sponge is really wet you will spoil the envelope.
Then slide the tip over the seal of the envelope to make the seal gluing. Seal the envelope and lay it aside.

It is a good idea to start with the first envelope at the very top of the dishtowel.
Since you can not avoid to moisten also a little part of the towel start the next envelope a little beneath the first position. This way the envelopes will always lay in a dry place.
If you reached the end of the dishtowel, fold it around to see a clear, dry surface again.

Step 6: Results, Final Thoughts, Improvement Ideas

Results
Sealing the 50+ envelopes and gluing the extra portage stamps on it took me less than an hour. So I think this little tool is a real helper.

Other use cases for this little helper can be:
- Replacement for a brush to paint something (because you have no brush at hand)
- Throw away brush (you are not willing to use one of your brushes, because the paint/rust remover/oil/whatever will spoil or destroy your brushes)

If you find new use cases please post them in the comments. I'll add them here.

Improvement Ideas
Thinking about painting with this tools maybe one can stamp the paint on the surface. If you cut a special form out of the sponge you can apply this form many times ...