I bought a small pocket trumpet from ebay. It came and turned out to be a nice instrument which I'd like to keep. Sorry for me, it lacked the original box. Trumpets don't like to be outside on their own, as anything can easily damage them. So I've needed to buy or build a preserver box for it. And I've chosen to build one, as I usually do.
First I've measured the dimensions of the trumpet and added approx 2cm from all sides to make a 3D model of the box in solidworks. I've used the sheet metal technique at the program as it enables the user to obtain a flattened output from a 3d model.
Step 1: Materials & Parts
I had a sheet of plywood taken from a scrap dump. It was 3mm thick and suitable for the job.
I wanted the box to be a bit like steampunky, cute and funny. So I've did a search on ebay for box parts that will make my box look like that.
Here are the ebay links I've used to buy the parts.
I've used a strap of an other bike bag but this box should have a leather strap like this
this maybe used for fixing the shoulder strap to the box, you can find better looking ones with a ring like mine if you search a bit more. As i have bought mine from the local boat hardware shop, I don't have a link.
later I've found this handle, much cheaper and looks nicer (bought 3 for later projects)
ornaments for the decoration of the box
Step 2: Laser Cutting Plywood
I've used a laser cutter / engraver to cut the plywood according to my flattened 3d model drawing. Pretty easy job.
Step 3: Engraving Plywood Pieces
This could have been done together with the cutting process but I wasn't planning to do engravings while I was cutting, so they are now separate steps.
I've drawn some decorations in a 2d drawing program and engraved them on to the parts already cut at the previous step. For engraving I've used the same laser cutter but with around %40 power.
Step 4: Stitching the Parts
Well this is the famous stitch and glue method for boat building but it also works for building many other things, including trumpet boxes.
You need to drill two holes at the adjacent edges of the parts of the box. Then put a metal wire thru the holes like seen at the pics, later turning the metal wire ends, making them squeeze the two plywood parts together. And by repeating this process to all of the edges of the plywood parts that will be fixed together to form the box.
I've made the bottom part and the lid part of the box separately so I've given more attention to making sure they align well after they are glued. As my plywood sheet was taken from a scrap and a bit bent, this step was important.
Then I've glued the parts together by using a small amount of 5 min epoxy glue. Later I've removed the wires by bending them up and down, creating metal fatique and causing the wires to break after several repetitions. I've also used pliers to bend and pull off the broken wires.
Step 5: Glassing the Inside
I've used a small amount of epoxy glue to hold the parts together but the box needs to be much stronger if it is going to really protect my nice instrument. So I've used fiberglass fabric to strengthen it from the inside. I've placed fabric cut to fit the inside and wetted it with normal one day curing epoxy and left to dry. This glassing step made the boxy very strong. I will be able to sit or even stand on it when complete.
fabric covering can also be appllied from the outside as that will make the box much stronger to withstand drops, scratches, even somebody. But I've preferred glassing the inside to make the box look as low tech as possible.
Step 6: Cutting Off the Excess Fiberglass
Later I've trimmed the excess fabric at the edges. Glass fibers with hardened epoxy on them are very thin and very strong. They are like very small needles and this step definitely requires gloves to be used.
Step 7: Assembling the Hinges
I've put the lid and the body of the box on top of each other and placed the hinge at the necessary location to test if the lid opens well by hand. Then marked the points to drill by a pencil. Drilled them with a drill bit just thick enough to open holes a bit tight for the m2 screws I've planned to use. I've chosen brass looking screws to fit the steampunky style.
Step 8: Assembling the Handle
Added the artificial leather handle which lies flush on the box when not used. I've used two screws to fix it and later replaced the nuts on them with the ones with plastic support ring inside that makes them quite difficult to get loose by themselves. I've also placed wide washers inside to spread the weight that will be applied to the plywood. As the inside was already glassed, with the help of this wide washers, the handle will be able to carry weights which are much more than a trumpet's.
Step 9: Putting on the Locks and Corner Protectors
I've assembled the locks and the corner protectors in a similar way.
I've used brass or brass looking parts as before. Now the box looks much nicer.
Step 10: Planning the Interior Cushioning
I've bought a fitness matress for building the interior cushion. By using the trumpet as the template, I've cut the parts necessary to cover the inside with several layers.
Step 11: Shoulder Strap Rings
I've bought these from a local marine market and they are general purpose rings for securing things at the side of a boat. And they are handmade from brass. I've fixed them to the sides as shown. Again I've used the nuts with the plastic at the end as these nuts will stay behind the cushioning and I don't want them to loosen in time.
Step 12: Mouthpiece Holder
I've used a wood stick appryximately 4x4 cm thick to make the mount for the mouthpiece. I've drilled a hole with my largest bit first and widened the hole into a conical shape with the conical abrasive bit. Then I've tested the wooden part onto its place in the box and with the mouthpiece itself. I've adjusted its position to enable the cushion at the lid to tightle press on it to keep the mouthpiece in place. A heavy mouthpiece loosely dangling around in the box can very badly damage a brass instrument.
After making sure of its position, I've glued the part onto its place at the box, applied small fiberglass fabric pieces to the sides while gluing to make the bond much stronger and long lasting.
Step 13: Gluing the Inside Cushions
I've glued the cushion parts by using the good old Bally. Of course I've did some testing first if it does the job well for this kind of matress and plywood.
A little waiting is necessary between the steps for the glue to cure.
And in the end I've obtained a nice cushioning that wraps the instrument securely and as tight as possible.
I've then left the instrument in the box overnight to see which cushion parts touch it and just scraped off some material from there to obtain a better cushioning and support to the instrument.
Step 14: Adding Ornaments
I've bought some metal ornaments from ebay to decorate the box and glued them onto the box like that. Also covered the box from outside by applying a coat of thick epoxy for extra protection and looks.
Step 15: Using It :D
Even before it was complete I've started using it in my city bike trips and after its completion I even took the trumpet to an 11 day bicycle tour covering parts of sweden, poland, germany and denmark. The trumpet survived the trip without scratch.
The box is rock solid, does the job and It takes a lot of attention too. :)