New construction images show this year's colourful Serpentine Gallery Pavilion by Spanish architects José Selgas and Lucía Cano, which is rapidly nearing completion ahead of its opening next week (+ slideshow).

The 15th Serpentine Pavilion is being built on a site in front of the gallery in London's Kensington Gardens, and was conceived as a "chrysalis-like" structure wrapped in coloured plastic that will filter the daylight like stained glass.

Photographers Freya Najade and Marcela Spadaro of NAARO have been documenting the construction process and have shared images of the almost-complete structure, which is due to open to the public on 25 June.

Strips and sheets of fluorine-plastic fabric (ETFE) have been used to create different effects in each area of the pavilion, which has a central meeting space and cafe area with four offshoots, which double as access tunnels.

The plastic is layered to form a double skin, which is wide enough in some places to create a passage around the edge of the pavilion.

"The spatial qualities of the pavilion only unfold when accessing the structure and being immersed within it," said the Madrid-based architects when the design was first unveiled in March.

"Each entrance allows for a specific journey through the space, characterised by colour, light and irregular shapes with surprising volumes," they added.

SelgasCano are the first Spanish designers to create the temporary pavilion, which is commissioned and built each year by the Serpentine Gallery in London's Kensington Gardens.

Their buildings often feature bright colours and transparent surfaces in their projects, which aim to combine new technologies and synthetic materials with an interest in the natural world. Examples include their own studio – a see-through woodland tunnel – and a recently completed office refurbishment in London with an orange plastic bulge in its facade.

Previous pavilion architects have included Sanaa, Peter Zumthor, Zaha Hadid, Herzog & de Meuron, Frank Gehry and Jean Nouvel. Last year's boulder-like pavilion was created by Chilean architect Smiljan Radic.

After their installation at the gallery, the pavilions are usually purchased by a private buyer, helping to cover up to 40 per cent of the cost of their construction. The remainder of the funding is provided by sponsorship.

The 2015 Serpentine Pavilion will host a number of parties, public talks and a series of evening events sponsored by fashion brand COS, and will close on 18 October.