This is what is being advertised as the “New” way to practice in limited spaces. Watch the new advertisement and then read what we were discussing more than 5 years ago.
One of the greatest joys I have experienced while writing this blog for the past 7 years is when readers write in with their own views and opinions. This is a very fine example of such a reader. His name is Felice Sobrero and after viewing my post he left a comment on his experience with the same issue I was covering which was being able to practice in a confined or volume conscious area adjacent to neighbors. Felice graciously agreed to share his more extended experiences with me on his solution to our common problem. I think you will be very impressed with the material he has contributed to our site and again I would like thank him for taking the time to share these more advanced and improved ideas than mine. You may also notice that Mr. Sobrero is a very meticulous craftsman in his approach to this project.
At this time I would like to introduce to you my new friend and college Mr. Felice Sobrero….
THE EXTERNAL MUTE
“What you can expect from it:
– Happily playing in a condo where you are surrounded by neighbors. During the day but not at night time.
– Reduce your trumpet volume by about 50%. Definitely more than a cup mute, but not nearly as much as a Yamaha Silent Brass.
– Variable sound reduction, depending on how deep you go in with the trumpet’s bell.
– Zero additional backpressure, unaltered playing feel, very natural sound reflected back directly to your ears.
– Quite cheap and easy to assemble, if you manage to get the right materials. Will cost less than many practice mutes.
– On the negative side: not so easy to find a comfortable position to sight-read music sheets.
What you need, tools and materials:
– As for tools, only scissors and a sharp knife or cutter. Normally you don’t need glue.
– Find a plastic trash/paper/garbage bin. As thick, as heavy, and as dead sounding as possible. I advise against metal and wood, because they tend to be resonant, while the bin should ideally dampen any vibration. Shape as cylindrical as possible; the opening about 3x a trumpet bell diameter (will be 2x tpt.dia. when completed). Length about 2x the opening diameter, but actually the longer the better (reflecting bottom as far as possible). My bin is 36 cm. (1′ 2”) diameter and 58 cm. (1′ 11”) long. 
– Mineral wool lining, as used for roofs and walls isolation. This is very cheap stuff to be found in hardware/building markets. (Alternatively thick and dense cottonwool). Thickness about 2.5 cm or 1 inch. Size: bin’s circumference x length, plus enough for the bottom.
– Acoustic foam plate, “cones” shaped, about 6-7 cm. (2.5”) thick including cones, flexible and soft. This stuff is quite expensive, mine was 15 Euros altogether. To be found in specialized Hi-Fi shops and markets, is normally sold for inside bass-reflex loudspeaker systems. But I have seen it for sale on EBay. Same size as the wool.
– Duct tape to seal the linings to the front border. (Just seal it, no matter how).
How to assemble it in 6 moves:
1) Cut a disk out of both lining materials, slightly larger than the inner bottom of the bin.
2) Prepare a sandwich, foam upside down with wool on top, and press it firmly into the bottom of the bin. Being slightly larger, it will stay in place by elastic compression.
3) Cut both materials in a rectangular shape, slightly larger than the circumference of the border, slightly shorter than the bin (will stay on top of the bottom disk).
4) Prepare again the sandwich, roll it onto itself and push it in the bin, against the bottom lining.
5) Let it unroll, and force the two edges in place, against each other. Once more, being slightly larger, the foam will make a pressure against the wool and the inner wall, staying firmly in place. That’s how you avoid using glue.
6) Making sure everything fits tight, seal the border of the bin and the linings together with duct tape or similar, so that nothing can come out. This also prevents the mineral wool to spread some unpleasant fibers around”.
We all thank you for your design and instruction Mr. Sobrero and wish you the very best for you and yours from thetrumpetblog.com.
You could probably mount a tabletop music stand on it.
I forgot to mention that, while not playing, the mute can stand on the floor doubling as a stable and shock-proof trumpet stand. The cones shaped surface at the bottom does not seal the bell, allowing a minimal air circulation.
And should anybody kick the whole thing by mistake, it will obviously fall on the side, but the same cones will hold the trumpet inside, preventing it from sliding out. I have been courageous enough to try…
Very good side benefit!