20" dia x 50cm deep
Made from 5mm flexible plywood. Excluding the skins it cost me around £68 with enough wood left over to build a repinique for £9 (cost of extra aluminium).
I put a Fibreskyn head on the top and a nylon head on the bottom. The sound is wonderful.
Construction does not need access to a workshop, and is well within the capabilities of any keen DIY'er with a few tools.
Full instructions available at Gerhard Totschnigs excellent drum building page http://sambaattac.gmxhome.de/DrumBuilding/Drumbuilding.htm
Mail me if you'd like to discuss any aspects of construction.
If you have difficulty finding 8mm M5 countersunk socket screws in the UK, I can recommend A2 A4 Fixings Ltd in Southampton.
Flexible plywood in the UK is available from William T Eden.
Home built repinique (son of surdo)
For this drum (no picture yet), I made some changes to the original construction details.
A minor point with the surdo is that two spanners are needed for tuning; each tensioning rod is secured by a nut at either end.
For the repinique I modified the bolts on the top counterhoop so that the end of the tensioning rod screws directly into the bolt, as shown in the diagram. This also gives a smoother surface for the hand to contact when playing.
As I was not certain of the sound I would get from a plywood rep' a prototype was constructed. Compared to a standard metal shell, the plywood used is less reflective and more absorbent of the sound. After some experimentation, I decided on the following for the shell construction.
Flexible plywood 5mm thick was used as it's easier to bend to a smaller radius.
The bearing edges and interior are lined with aluminium foil, glued on with PVA adhesive.
Because of the much greater tension on the counterhoops, the joinining strip is secured by 2 bolts either side of the join. Otherwise the hoop will distort.
For the heads, I used Remo Diplomat batter heads, coated on the top head and clear on the bottom.