ByPost, the Scotland-based start-up whose smartphone app converts electronic messages into picture postcards and other conventional post items, is seeking to raise up to £1.5 million via a new issue of 760 new shares.

The company has seen more than 650,000 iPhone downloads of ByPost Postcard Maker, its core "mobile-to-physical" application, earning more than £500,000 of sales. It is now unveiling plans to release six new mobile apps on both iOS and Android platforms to coincide with the £2000-a-share funding round.

ByPost, which has been a top-­selling app in 22 countries according to audited rankings, is the brainchild of the Bridge of Allan-based serial entrepreneur Luke Heron, 35, chief executive and majority shareholder. Heron has launched numerous businesses since dropping out of school aged 15, including ventures in the fields of rare wines, children's books, and environmentally friendly children's clothes.

ByPost's fundraising prospectus shows last year's actual earnings of £245,000, being projected to climb to £1m in the current year, £9m in year three and £27.4m in year four - £12.1m of which is presented as profit.

The firm stresses the advantages of its "eco-system", in which computer code can be shared across diverse applications, allowing convenient cross-selling from a common user database. Of its existing 191,000 user accounts, currently 67,000 are active spending accounts, with 80% based in the UK.

The new apps being launched over the course of this year are Photobooth, which allows passport quality photos to be taken and posted to the home, Sweet Jar, an online pick-and-mix function and Casemaker, which allows the design and home delivery of hard plastic mobile device cases. The others are Treasurebox, an app facilitating the dispatch of gifts, and Stocking Filler, which allows the multiple purchase of low-value goods for Christmas stockings.

Heron told the Sunday Herald: "We already have unsolicited commitments of £700,000 from existing shareholders and a few new business angels, most of whom are ByPost users. We have a number of venture capital meetings scheduled in the coming weeks, and I'm confident the round will conclude quickly. It helps that the investment qualifies for the Enterprise Investment Scheme [offering tax breaks for investment in small unquoted companies].

"It's taken a long time to create this hub, but we're now at the stage we can bolt on new apps quickly enough to respond immediately to any passing retail trend."