The LSP-4 is seen here on the coupling jig, which is where the front, centre and rear fuselage are coupled together. As you can see, LSP-4 has completed its coupling. Once this is done, the fuselage will be taken to the "foreign objects detection jig", on which the fuselage is rotated. If there are any foreign objects left behind in the fuselage by mistake (e.g. tools, screws, keys, spectacles), they will make a sound when the aircraft is rotated.
Foreign Objects Damage (FOD) --- in which a running aircraft gets damaged because of objects left inside it, or on the runway or taxiway --- is taken very seriously in the IAF... and also in HAL.
The next stage after this is to install the engine and the two wings. The LSP-4's wings are being assembled separately; you can see one of the technician who are doing it. Take a look at the individual struts... that are machined from metal billets. The entire "framework" of the wing is a mixture of metal and composites. This forms the skeleton over which the "aircraft skin" is placed.
LSP-4 will carry and test all the aircraft and avionics systems which have not been fitted on LSP-3. From LSP-5 onwards, all the LSPs will carry the entire range of systems which will be fitted on the production version LCAs.
And LSP-5 fuselage is also under way.