The calico is a bit translucent when stretched to cover, so the wood frame will show through a bit. I didn't like the look of this so covered the visible parts of the frame with standard grey gaffer tape, which was similar enough in colour to the Rockwool to give a uniform finish over the panel faces. You could probably achieve the same with a suitably drab coloured paint
Materials were;
Rockwool RW5 1200 x 600 x 100mm
Kiln dried general purpose wood 2400 x 38 x 19 mm (from B&Q)
Calico 160cm wide (CALICO NATURAL) from Remnant Kings
Corner brackets from Screwfix
MSL Firecheck - fire retardant spray
In hindsight I've learned that Rockwool RW3 may have been a better choice than RW5 for basstraps, although at 100mm depth opinions differ. It's certainly been effective in use as is.
I've no idea how much benefit the open frame construction has in practice, but thought it may be worth building them such that as much absorptive surface as possible was presented.
Comments welcome!
Cheers,
Jennifer
First build the frame for the back of the trap. Upright posts from the same wood are attached with brackets;
Next staple the calico cover for the back face onto the frame;
Trim Rockwool edges to fit with a sharp knife then put in frame. The rear face of the Rockwool doesn't need trimmed as it lies flat on the frame.
Attach the top frame with four countersunk screws for a flush finish;
Rear view of fully framed panel;
Cover front and side with calico, stapling to back. I used something like "hospital corners" to get a smooth finish;
Finished article;